And to show how entire the neglect and confusion have been, they speak in the same breath of all these explosions, and of the explosion of a mixture of hydrogen and oxygen, the result of which, instead of being a gas or an enlargement of bulk, a positive quantity, is a negative one. It is a vacuum, in a popular sense, because the produce is water. The result is an implosion (to coin a word), not an explosion .... ["Gas-light," Westminster Review, October 1829]
In early use often in reference to effect of deep sea pressures, or in phonetics. Figurative sense is by 1960.
"sudden pitch to one side," 1784, from earlier lee-larches (1765), a nautical term for "the sudden roll which a ship makes to lee-ward in a high sea, when a large wave strikes her, and bears her weather-side violently up, which depresses the other in proportion" ["Complete Dictionary of Arts and Sciences," London 1765]. This is perhaps from French lacher "to let go," from Latin laxus (see lax).
When a Ship is brought by the Lee, it is commonly occaſsioned by a large Sea, and by the Neglect of the Helm's-man. When the Wind is two or three Points on the Quarter, the Ship taking a Lurch, brings the Wind on the other Side, and lays the Sails all dead to the Maſt; as the Yards are braced up, ſhe then having no Way, and the Helm being of no Service, I would therefore brace about the Head ſails ſharp the other Way .... [John Hamilton Moore, Practical Navigator, 8th ed., 1784]
early 15c., in law, "wrong action; a failure, offense or illegal act," especially on the part of a public official, from Anglo-French misprisoun, mesprisioun "mistake, error, wrong action or speech," (Old French mesprision "mistake, wrongdoing, fault, blame, crime"), from mespris, past participle of mesprendre "to mistake, act wrongly, trespass, transgress, break a law," from mes- "wrongly" (see mis- (2)) + prendre "take," from Latin prendere, contracted from prehendere "to seize" (from prae- "before," see pre-, + -hendere, from PIE root *ghend- "to seize, take").
In general, "criminal neglect in respect to the crime of another," especially in connection with felonies, to indicate a passive complicity, as by concealment. In 16c., misprision of treason was used for lesser degrees of guilt (those not subject to capital punishment), especially for knowing of treasonable actions or plots without assenting to them, but not informing the authorities. This led to the common supposition in legal writers that the word means etymologically "failure to denounce" a crime.
1816, in the figurative sense of "icy reception, studied neglect or indifference," first in Sir Walter Scott, probably originally a literal figure (see cold (adj.)), but commonly used with a punning reference to "cold shoulder of mutton," considered a poor man's dish and thus, perhaps, something one would set out for an unwanted guest with deliberate intention to convey displeasure.
How often have we admired the poor knight, who, to avoid the snares of bribery and dependence, was found making a second dinner from a cold shoulder of mutton, above the most affluent courtier, who had sold himself to others for a splendid pension! ["No Fiction," 1820]
Originally with to show, later to give. As a verb from 1845; related: cold-shouldered. Also compare cold roast, old slang for "something insignificant." Cold pig was a 19c. term for throwing cold water on a sleeping person to wake him or her.
Old English læfan "to allow to remain in the same state or condition; to let remain, allow to survive; to have left (of a deceased person, in reference to heirs, etc.); to bequeath (a heritage)," from Proto-Germanic *laibjanan (source also of Old Frisian leva "to leave," Old Saxon farlebid "left over"), causative of *liban "remain" (source of Old English belifan, German bleiben, Gothic bileiban "to remain"), from PIE root *leip- "to stick, adhere."
The Germanic root seems to have had only the sense "remain, continue" (which was in Old English as well but has since become obsolete), which also is in Greek lipares "persevering, importunate." But this usually is regarded as a development from the primary PIE sense of "adhere, be sticky" (compare Lithuanian lipti, Old Church Slavonic lipet "to adhere," Greek lipos "grease," Sanskrit rip-/lip- "to smear, adhere to."
Originally a strong verb (past participle lifen), it early switched to a weak form. Meaning "go away, take one's departure, depart from; leave behind" (c. 1200) comes from notion of "leave behind" (as in to leave the earth "to die;" to leave the field "retreat"). From c. 1200 as "to stop, cease; give up, relinquish, abstain from having to do with; discontinue, come to an end;" also "to omit, neglect; to abandon, forsake, desert; divorce;" also "allow (someone) to go."
Colloquial use for "let, allow" is by 1840, said by OED to be chiefly American English. Not related to leave (n.). To leave out "omit" is from late 15c. To leave (something) alone is from c. 1400; to leave (something) be is from 1825. To leave (something/nothing) to be desired is from 1780. To leave it at that is from 1902. Leave off is from c. 1400 as "cease, desist" (transitive); early 15c. as "stop, make an end" (intransitive).
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 would be "let go through weariness, neglect."
"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.
c. 1200, "opposite of right," probably from Kentish and northern English forms of Old English *lyft "weak; foolish" (in lyft-adl "lameness, paralysis"). Compare East Frisian luf, Dutch dialectal loof "weak, worthless").
Sense of "opposite of right" is from the left being usually the weaker hand), a derived sense also found in cognate Middle Dutch and Low German luchter, luft. Compare Lithuanian kairys "left" and Lettish kreilis "left hand" both from a root that yields words for "twisted, crooked."
The usual Old English winstre/winestra "left" (adj.); "left hand," literally "friendlier," a euphemism used superstitiously to avoid invoking the unlucky forces connected with the left side (compare sinister). The Kentish word itself might have been originally a taboo replacement, if instead it represents PIE *laiwo- "considered conspicuous" (represented in Greek laios, Latin laevus, and Russian levyi). Greek also uses a euphemism for "left," aristeros "the better one" (compare also Avestan vairyastara- "to the left," from vairya- "desirable").
Meaning "being on the left-hand side" is from c. 1300. As an adverb from early 14c. For political senses, see left (n.). Used at least since c. 1600 in various senses of "irregular, illicit;" earlier proverbial sense was "opposite of what is expressed" (mid-15c.), for example over the left (shoulder) "not at all," added to a statement to negate or neglect what was just said (1705). To have two left feet "be clumsy" is attested by 1902.
Phrase out in left field "out of touch with pertinent realities" is attested from 1944, from the baseball fielding position that tends to be far removed from the play (left field in baseball attested by 1867; the fielding positions are from the point of view of the batter). The Parisian Left Bank (of the River Seine) has been associated with intellectual and artistic culture at least since 1893; Left Coast "Pacific Coast of the U.S." is by 1980s.
German link, Dutch linker "left" are said to be not directly related to these, being instead from Old High German slinc and Middle Dutch slink "left," related to Swedish linka "limp," slinka "dangle," and Old English slincan "crawl" (Modern English slink).