"small sack," c. 1200, bagge, probably from Old Norse baggi "pack, bundle," or a similar Scandinavian source. OED rejects connection to other Germanic words for "bellows, belly" as without evidence and finds a Celtic origin untenable. In some senses perhaps from Old French bague, which is also from Germanic.

As disparaging slang for "woman" it dates from 1924 in modern use (but various specialized senses of this are much older, and compare baggage). The meaning "person's area of interest or expertise" is by 1964, from African-American vernacular, from jazz sense of "category," probably via notion of putting something in a bag. The meaning "fold of loose skin under the eye" is by 1867. Related: bags.

To be left holding the bag (and presumably nothing else), "cheated, swindled" is attested by 1793. Many figurative senses, such as the verb meaning "to kill game" (1814) and its colloquial extension to "catch, seize, steal" (1818) are from the notion of the game bag (late 15c.) into which the product of the hunt was placed. This also probably explains modern slang in the bag "assured, certain" (1922, American English).

To let the cat out of the bag "reveal the secret" is from 1760. The source is probably the French expression Acheter chat en poche "buy a cat in a bag," which is attested in 18c. French and explained in Bailey's "Universal Etymological English Dictionary" (1736), under the entry for To buy a pig in a poke as "to buy a Thing without looking at it, or enquiring into the Value of it." (Similar expressions are found in Italian and German; and in English, Wycliffe (late 14c.) has To bye a catte in þo sakke is bot litel charge). Thus to let the cat out of the bag would be to inadvertently reveal the hidden truth of a matter one is attempting to pass off as something better or different, which is in line with the earliest uses in English.

Sir Joseph letteth the cat out of the bag, and sheweth principles inimical to the cause of true philosophy, by wishing to make great men Fellows, instead of wise men ["Peter Pindar," "Peter's Prophecy," 1788]

general common name of birds of the genus Corvus (the larger sort being sometimes called ravens), Old English crawe, which is held to be imitative of the bird's cry. Compare Old Saxon kraia, Dutch kraai, Old High German chraja, German Kräke.

Noted for sagacity and sociability. The British and North American species are very similar.  Phrase as the crow flies "in a straight line" is from 1810; the image is attested in different form from 1800. 

American English figurative phrase eat crow "do or accept what one vehemently dislikes and has opposed defiantly, accept things which, though not unbearable, are yet scarcely to be wished for," is attested by 1870 (originally often eat boiled crow), and seems to be based on the notion that the bird is edible when boiled but hardly agreeable.

There was an oft-reprinted mid-19c. joke about a man who, to settle a bet that he could eat anything, agrees to eat a boiled crow. As he with great difficulty swallows the first to mouthfuls, he says to the onlookers, "I can eat crow, but I don't hanker arter it." The joke is attested by 1854 (Walter Etecroue turns up 1361 in the Calendar of Letter Books of the City of London).

I tried my best to eat crow, but it was too tough for me. "How do you like it?" said the old man, as, with a desperate effort, he wrenched off a mouthful from a leg. "I am like the man," said I, "who was once placed in the same position: 'I ken eat crow, but hang me if I hanker arter it.'" "Well," says the captain, "it is somewhat hard; but try some of the soup and dumplings and don t condemn crow-meat from this trial, for you shot the grandfather and grandmother of the flock: no wonder they are tough; shoot a young one next time." "No more crow-meat for me, thank you," said I. [James G. Swan, "The Northwest Coast, or Three Years' Residence in Washington Territory," New York, 1857] 

The image of a crow's foot for the wrinkles appearing with age at the corner of the eye is from late 14c. ("So longe mote ye lyve Til crowes feet be growen under youre ye." [Chaucer, Troilus and Criseyde, c. 1385]).

Middle English kēpen, from late Old English cepan (past tense cepte) "to seize, hold; seek after, desire," also "to observe or carry out in practice; look out for, regard, pay attention to," from Proto-Germanic *kopjan, which is of uncertain origin. Old English cepan was used c. 1000 to render Latin observare, so perhaps it is related to Old English capian "to look" (from Proto-Germanic *kap-), which would make the basic sense "to keep an eye on, see to it."

The word prob. belonged primarily to the vulgar and non-literary stratum of the language; but it comes up suddenly into literary use c. 1000, and that in many senses, indicating considerable previous development. [OED]

The senses exploded in Middle English: "to guard, defend" (12c.); "restrain (someone) from doing something" (early 13c.); "take care of, look after; protect or preserve (someone or something) from harm, damage, etc." (mid-13c.); "preserve, maintain, carry on" a shop, store, etc. (mid-14c.); "prevent from entering or leaving, force to remain or stay" (late 14c.); "preserve (something) without loss or change," also "not divulge" a secret, private information, etc., also "to last without spoiling" (late 14c.); "continue on" (a course, road, etc.), "adhere to" a course of action (late 14c.); "stay or remain" (early 15c.); "to continue" (doing something) (mid-15c.). It is used to translate both Latin conservare "preserve, keep safe" and tenere "to keep, retain."

From 1540s as "maintain for ready use;" 1706 as "have habitually in stock for sale." Meaning "financially support and privately control" (usually in reference to mistresses) is from 1540s; meaning "maintain in proper order" (of books, accounts) is from 1550s.

To keep at "work persistently" is from 1825; to keep on "continue, persist" is from 1580s. To keep up is from 1630s as "continue alongside, proceed in pace with," 1660s as "maintain in good order or condition, retain, preserve," 1680s as "support, hold in an existing state." To keep it up "continue (something) vigorously" is from 1752. To keep to "restrict (oneself) to" is from 1711. To keep off (trans.) "hinder from approach or attack" is from 1540s; to keep out (trans.) "prevent from entering" is from early 15c.

1520s, also monkie, munkie, munkye, etc., not found in Middle English (where ape was the usual word); of uncertain origin, but likely from an unrecorded Middle Low German *moneke or Middle Dutch *monnekijn, a colloquial word for "monkey," originally a diminutive of some Romanic word, compare French monne (16c.); Middle Italian monnicchio, from Old Italian monna; Spanish mona "ape, monkey." In a 1498 Low German version of the popular medieval beast story Roman de Renart ("Reynard the Fox"), Moneke is the name given to the son of Martin the Ape; transmission of the word to English might have been via itinerant entertainers from the German states.

The Old French form of the name is Monequin (recorded as Monnekin in a 14c. version from Hainault), which could be a diminutive of some personal name, or it could be from the general Romanic word, which may be ultimately from Arabic maimun "monkey," literally "auspicious," a euphemistic usage because the sight of apes was held by the Arabs to be unlucky [Klein]. The word would have been influenced in Italian by folk etymology from monna "woman," a contraction of ma donna "my lady."

In general, any one of the primates except man and lemurs; in more restricted use, "an anthropoid ape or baboon;" but popularly used especially of the long-tailed species often kept as pets. Monkey has been used affectionately or in pretended disapproval of a child since c. 1600. As the name of a type of modern popular dance, it is attested from 1964.

Monkey suit is from 1876 as a type of child's suit; by 1918 as slang for "fancy dress clothes or uniform." To make a monkey of "make a fool of" is attested from 1851. To have a monkey on one's back "be addicted" is 1930s narcotics slang, though the same phrase in the 1860s meant "to be angry." There is a story in the Sinbad cycle about a tormenting ape-like creature that mounts a man's shoulders and won't get off, which may be the root of the term. In 1890s British slang, to have a monkey up the chimney meant "to have a mortgage on one's house." The Japanese three wise monkeys ("see no evil," etc.) are attested in English by 1891.

1833, "one who embodies the person or character of another;" 1840 as "one who infuses (something) with a personality;" 1842 as "dramatic actor, one who plays a part on stage," from impersonate with Latinate agent noun suffix. Meaning "one who imitates the manners and speech of another" for entertainment (by 1921) perhaps grew from older theatrical use of female impersonator (1876), male impersonator (1874), both once popular stage acts; the first example of the latter was perhaps Miss Ella Wesner, who had a vogue c. 1870: In Britain, blackface performers were called negro impersonators (1906). As a fem. formation, impersonatrix, as if from Latin, is from 1847; impersonatress, as if from French, is from 1881.

Her [Wesner's] impersonation were a genuine surprise and her success was so pronounced that in a short period a host of imitators made their appearance. Her most successful rivals were Bessie Bonehill, Millie Hilton and Vesta Tilley, all of London. [M.B Leavitt, "Fifty Years in Theatrical Management," New York, 1912]

There is no member of a minstrel company who gets a better salary than a good female impersonator, the line being considered a very delicate one, requiring a high style of art in its way to judge where fun stops and bad taste begins, with decision enough on the part of the performer to stop at the stopping place. ["The Ancestry of Brudder Bones," Harper's New Monthly Magazine, April 1879]

The most fascinating performer I knew in those days was a dame named Metcalfe who was a female female impersonator. To maintain the illusion and keep her job, she had to be a male impersonator when she wasn't on. Onstage she wore a wig, which she would remove at the finish, revealing her mannish haircut. "Fooled you!" she would boom at the audience in her husky baritone. Then she would stride off to her dressing room and change back into men's clothes. She fooled every audience she played to, and most of the managers she worked for, but her secret was hard to keep from the rest of the company. [Harpo Marx, "Harpo Speaks"]

"terminal part of the leg of a vertebrate animal," Old English fot "foot," from Proto-Germanic *fōts (source also of Old Frisian fot, Old Saxon fot, Old Norse fotr, Danish fod, Swedish fot, Dutch voet, Old High German fuoz, German Fuß, Gothic fotus "foot"), from PIE root *ped- "foot." Plural form feet is an instance of i-mutation.

The linear measure was in Old English (the exact length has varied over time), this being considered the length of a man's foot; a unit of measure used widely and anciently. In this sense the plural is often foot. The current inch and foot are implied from measurements in 12c. English churches (Flinders Petrie, "Inductive Metrology"), but the most usual length of a "foot" in medieval England was the foot of 13.2 inches common throughout the ancient Mediterranean. The Anglo-Saxon foot apparently was between the two. All three correspond to units used by the Romans, and possibly all three lengths were picked up by the Anglo-Saxons from the Romano-Britons. "That the Saxon units should descend to mediæval times is most probable, as the Normans were a ruling, and not a working, class." [Flinders Petrie, 1877]. The medieval Paul's Foot (late 14c.) was a measuring standard cut into the base of a column at the old St. Paul's cathedral in London. The metrical foot (late Old English, translating Latin pes, Greek pous in the same sense) is commonly taken to represent one rise and one fall of a foot: keeping time according to some, dancing according to others.

In Middle English also "a person" (c. 1200), hence non-foot "nobody." Meaning "bottom or lowest part of anything eminent or upright" is from c. 1200. Of a bed, grave, etc., from c. 1300. On foot "by walking" is from c. 1300. To get off on the wrong foot is from 1905 (the right foot is by 1907); to put one's best foot foremost first recorded 1849 (Shakespeare has the better foot before, 1596); Middle English had evil-foot (adv.) "through mischance, unluckily." To put one's foot in (one's) mouth "say something stupid" is attested by 1942; the expression put (one's) foot in something "make a mess of it" is from 1823. To have one foot in the grave "be near death" is from 1844. Colloquial exclamation my foot! expressing "contemptuous contradiction" [OED] is attested by 1923, probably euphemistic for my ass in the same sense, which dates to 1796 (also see eyewash).

early 13c., "repulsive old woman" (rare before 16c.), probably from Old English hægtes, hægtesse "witch, sorceress, enchantress, fury," shortened on the assumption that -tes was a suffix. The Old English word is from Proto-Germanic *hagatusjon, which is of unknown origin. Dutch heks, German Hexe "witch" are similarly shortened from cognate Middle Dutch haghetisse, Old High German hagzusa.

The first element probably is cognate with Old English haga "enclosure, portion of woodland marked off for cutting" (see hedge (n.)). Old Norse had tunriða and Old High German zunritha, both literally "hedge-rider," used of witches and ghosts. The second element in the prehistoric compound may be connected with Norwegian tysja "fairy; crippled woman," Gaulish dusius "demon," Lithuanian dvasia "spirit," from PIE *dhewes- "to fly about, smoke, be scattered, vanish."

One of the magic words for which there is no male form, suggesting its original meaning was close to "diviner, soothsayer," which were always female in northern European paganism, and hægtesse seem at one time to have meant "woman of prophetic and oracular powers" (Ælfric uses it to render the Greek "pythoness," the voice of the Delphic oracle), a figure greatly feared and respected. Later, the word was used of village wise women.

Haga is also the haw- in hawthorn, which is an important tree in northern European pagan religion. There may be several layers of folk etymology here. Confusion or blending with heathenish is suggested by Middle English hæhtis, hægtis "hag, witch, fury, etc.," and haetnesse "goddess," used of Minerva and Diana.

If the hægtesse once was a powerful supernatural woman (in Norse it is an alternative word for Norn, any of the three weird sisters, the equivalent of the Fates), it might originally have carried the hawthorn sense. Later, when the pagan magic was reduced to local scatterings, it might have had the sense of "hedge-rider," or "she who straddles the hedge," because the hedge was the boundary between the civilized world of the village and the wild world beyond. The hægtesse would have a foot in each reality. Even later, when it meant the local healer and root collector, living in the open and moving from village to village, it may have had the mildly pejorative Middle English sense of hedge- (hedge-priest, etc.), suggesting an itinerant sleeping under bushes. The same word could have contained all three senses before being reduced to its modern one.

Old English lætan (Northumbrian leta) "to allow; to leave behind, depart from; leave undone; bequeath," also "to rent, put to rent or hire" (class VII strong verb; past tense let, leort, past participle gelæten), from Proto-Germanic *letan (source also of Old Saxon latan, Old Frisian leta, Dutch laten, Old High German lazan, German lassen, Gothic letan "to leave, let"), from PIE *led-, extended form of root *‌‌lē- "to let go, slacken." If that derivation is correct, the etymological sense might be "let go through weariness, neglect."

The idea of slackening lies at the root of both applications of the term. When we speak of letting one go, letting him do something, we conceive him as previously restrained by a band, the loosening or slackening of which will permit the execution of the act in question. ... At other times the slackness is attributed to the agent himself, when let acquires the sense of being slack in action, delaying or omitting to do. [Hensleigh Wedgwood, "A Dictionary of English Etymology," 1859] 

He points to similar developments in French laisser "to let" from Latin laxare "to slacken," German lassen "to permit, to let," from dialectal lass "loose."

"The shortening of the root vowel ... has not been satisfactorily explained" [OED]. Of blood, from late Old English. Other Old and Middle English senses include "regard as, consider; behave toward; allow to escape; pretend;" to let (someone) know and to let fly (arrows, etc.) preserve the otherwise obsolete sense of "to cause to."

To let (someone) off "allow to go unpunished, excuse from service" is from 1814. To let on is from 1725 as "allow (something) to be known, betray one's knowledge of," 1822 as "pretend" (OED finds a similar use in the phrase never let it on him in a letter from 1637). To let out is late 12c. as "allow to depart" (transitive); intransitive use "be concluded," of schools, meetings, etc., is from 1888, considered by Century Dictionary (1895) to be "Rural, U.S." Of garments, etc., late 14c.

Let alone "abstain from interfering with" is in Old English; the phrase in the sense "not to mention, to say nothing of" is from 1812. To let (something) be "leave it alone" is from c. 1300; let it be "let it pass, leave it alone" is from early 14c. To let go is from c. 1300 as "allow to escape," 1520s as "cease to restrain," 1530s as "dismiss from one's thoughts." Let it go "let it pass, no matter" is as old as Chaucer's Wife of Bath: "But age allas Hath me biraft my beautee Lat it go, far wel, the deuel go ther with!" [c. 1395]. Let me see "show me" is from c. 1300.