c. 1300, naturel, "of one's inborn character; hereditary, innate, by birth or as if by birth;" early 14c. "of the world of nature (especially as opposed to man)," from Old French naturel "of nature, conforming to nature; by birth," and directly from Latin naturalis "by birth, according to nature," from natura "nature" (see nature).

Of events, features, etc., "existing in nature as a result of natural forces" (that is, not caused by accident, human agency, or divine intervention), late 14c. From late 14c. of properties, traits, qualities, "proper, suitable, appropriate to character or constitution;"  from late 15c. as "native, native-born." Also late 15c. as "not miraculous, in conformity with nature," hence "easy, free from affectation" (c. 1600). Of objects or substances, "not artificially cultivated or created, existing in nature" c. 1400. As a euphemism for "illegitimate, bastard" (of children), it is recorded from c. 1400, on the notion of blood kinship (but not legal status).

Natural science, that pertaining to physical nature, is from late 14c.;  natural history meaning more or less the same thing is from 1560s (see history).  Natural law "the expression of right reason or the dictate of religion inhering in nature and man and having ethically binding force as a rule of civil conduct" is from late 14c. Natural order "apparent order in nature" is from 1690s. Natural childbirth is attested by 1898. Natural life, usually in reference to the duration of life, is from mid-15c.; natural death, one without violence or accident, is from mid-15c. To die of natural causes is from 1570s.

"give motion to by the act of pulling," c. 1200, drauen, spelling alteration of Old English dragan "to drag, to draw, protract" (class VI strong verb; past tense drog, past participle dragen), from Proto-Germanic *draganan "to draw, pull" (source also of Old Norse draga "to draw, drag, pull," Old Saxon dragan "to carry," Old Frisian drega, draga, Middle Dutch draghen "to carry, bring, throw," Old High German tragan "carry, bring, lead," German tragen "to carry, bear"), from PIE root *dhregh- (see drag (v.)).

Sense of "make a line or figure" (by "drawing" a pencil across paper) is from c. 1200. Meaning "remove or extract (a weapon) by pulling" is from late 12c., originally of a sword. Sense of "to pull (a bowstring)" is from c. 1200. To draw a criminal (drag him at the tail of a horse to the place of execution) is from c. 1300.

Meaning "select one (from a number of lots, etc.)" is from c. 1300. Sense of "bring (a crowd, an audience, etc.) by inducement or attraction" is from 1580s. Of a ship or boat, "to displace (a specified amount) of water," 1550s. In card-playing, "to take or receive (a card)," by 1772; draw-poker is by 1850. To draw out "lengthen, protract" is from 1550s; to draw the line in the figurative sense of "make a limit" is by 1793. To draw blood is from c. 1400.

The difference between [Draw Poker] and Poker is, that the player can draw from the pack as many cards as he may wish,—not exceeding five,—which must be given him by the dealer; but previous to drawing he must take from his original hand the game number as he may wish to draw, and lay them in the centre of the table. ["Bohn's New Hand-Book of Games," Philadelphia, 1850]

Old English losian "be lost, perish," from los "destruction, loss," from Proto-Germanic *lausa- (source also of Old Norse los "the breaking up of an army;" Old English forleosan "to lose, destroy," Old Frisian forliasa, Old Saxon farliosan, Middle Dutch verliesen, Old High German firliosan, German verlieren, as well as English -less, loss, loose). The Germanic word is from PIE *leus-, an extended form of root *leu- "to loosen, divide, cut apart."

The verb also is merged with, or has taken the (weaker) sense of, the related Middle English leese "be deprived of, lose" (Old English leosan, a class II strong verb whose past participle loren survives in forlorn and love-lorn), from Proto-Germanic *leusanan (source also of Old High German virliosan, German verlieren, Old Frisian urliasa, Gothic fraliusan "to lose").

Hence lose in the transitive senses "part with accidentally, be deprived of, miss the possession or knowledge of" (money, blood, sleep, hair, etc.), c. 1200; "fail to keep, lose track of" (mid-13c.). Meaning "fail to preserve or maintain" is from mid-15c. Meaning "fail to gain or win" (something) is from c.1300; intransitive meaning "fail to win" (a game, contest, lawsuit, etc.) is from late 14c. Meaning "to cause (someone) to lose his way" is from 1640s; meaning "cease to have, be rid of" (something unwanted) is from 1660s.

To lose heart "become discouraged" is from 1744; to lose (one's) heart "fall in love" is from 1630s. To lose (one's) mind "become insane" is attested from c. 1500. To lose out "fail" is 1858, American English. To lose it "become distraught, break down and lose control of oneself" is by 1990s; the it probably being one's self-control or grip on reality. Related: Lost; losing.

late 14c., "statement, belief, or practice handed down from generation to generation," especially "belief or practice based on Mosaic law," from Old French tradicion "transmission, presentation, handing over" (late 13c.) and directly from Latin traditionem (nominative traditio) "a delivering up, surrender, a handing down, a giving up" (also "a teaching, instruction," and "a saying handed down from former times"). This is a noun of action from past-participle stem of tradere "deliver, hand over," from trans- "over" (see trans-) + dare "to give" (from PIE root *do- "to give"). The word is a doublet of treason (q.v.). Meaning "a long-established custom" is from 1590s. The notion is of customs, ways, beliefs, doctrines, etc. "handed down" from one generation to the next.

Tradition is not solely, or even primarily, the maintenance of certain dogmatic beliefs; these beliefs have come to take their living form in the course of the formation of a tradition. What I mean by tradition involves all those habitual actions, habits and customs, from the most significant religious rite to our conventional way of greeting a stranger, which represent the blood kinship of 'the same people living in the same place'. ... We become conscious of these items, or conscious of their importance, usually only after they have begun to fall into desuetude, as we are aware of the leaves of a tree when the autumn wind begins to blow them off—when they have separately ceased to be vital. Energy may be wasted at that point in a frantic endeavour to collect the leaves as they fall and gum them onto the branches: but the sound tree will put forth new leaves, and the dry tree should be put to the axe. [T.S. Eliot, "After Strange Gods"]

fifteenth letter of the alphabet, from a character that in Phoenician was called  'ain (literally "eye") and represented "a very peculiar and to us unpronounceable guttural" [Century Dictionary]. The Greeks also lacked the sound, so when they adopted the Phoenician letters they arbitrarily changed O's value to a vowel. (Thus there is no grounds for the belief that the form of the letter represents the shape of the mouth in pronouncing it.) The Greeks later added a special character for "long" O (omega), and the original became "little o" (omicron).

In Middle English and later colloquial use, o or o' can be an abbreviation of on or of, and is still literary in some words (o'clock, Jack-o'-lantern, tam-o'-shanter, cat-o'-nine-tails, will-o'-the-wisp, etc.).

O' the common prefix in Irish surnames is from Irish ó, ua (Old Irish au, ui) "descendant." 

The "connective" -o- is the usual connecting vowel in compounds taken or formed from Greek, where it often is the vowel in the stem. "[I]t is affixed, not only to terms of Greek origin, but also to those derived from Latin (Latin compounds of which would have been formed with the L. connecting or reduced thematic vowel, -i), especially when compounds are wanted with a sense that Latin composition, even if possible, would not warrant, but which would be authorized by the principles of Greek composition." [OED]

As "zero" in Arabic numerals it is attested from c. 1600, from the similarity of shape. Similarly the O blood type (1926) was originally "zero," denoting the absence of A and B agglutinogens.

As a gauge of track in model railroads, by 1905. For o as an interjection of fear, surprise, joy, etc., see oh.

The use of the colloquial or slang -o suffix in wino, ammo, combo, kiddo, the names of the Marx Brothers, etc., "is widespread in English-speaking countries but nowhere more so than in Australia" [OED].

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.

early 15c., "servants of a household," from Latin familia "family servants, domestics collectively, the servants in a household," thus also "members of a household, the estate, property; the household, including relatives and servants," abstract noun formed from famulus "servant, slave," which is of unknown origin.

The Latin word rarely appears in the sense "parents with their children," for which domus (see domestic (adj.)) was used. Derivatives of famulus include famula "serving woman, maid," famulanter "in the manner of a servant," famulitas "servitude," familiaris "of one's household, private," familiaricus "of household slaves," familiaritas "close friendship."

In English, sense of "collective body of persons who form one household under one head and one domestic government, including parents, children, and servants, and as sometimes used even lodgers or boarders" [Century Dictionary] is from 1540s. From 1660s as "parents with their children, whether they dwell together or not," also in a more general sense, "persons closely related by blood, including aunts, uncles, cousins;" earlier "those who descend from a common progenitor, a house, a lineage" (1580s). Hence, "any group of things classed as kindred based on common distinguishing characteristics" (1620s); as a scientific classification, between genus and order, from 1753.

Latin familia often was glossed in Old English by hired, hyred "household, family, retinue" (for which see hide (n.2), and also by hiwscipe, hiwræden, hiwan "members of a family, household,  or religious house," which is cognate with Old Norse hjon "one of the household; married couple, man and wife; domestic servant," and with Old High German hiwo "husband," hiwa "wife," also with Lithuanian šeimyna "family," Gothic haims "village," Old English ham "village, home" (see home (n.)). A 15c. glossary has, for Latin familia, Middle English a menge, from Anglo-French maisnie "the household, the whole attendance upon the personal establishment of the feudal lord."

As an adjective from c. 1600; with the meaning "suitable for a family," by 1807. Family values is recorded by 1966. Phrase in a family way "pregnant" is from 1796. Family circle is 1809; family man "man devoted to wife and children, man inclined to lead a domestic life" is 1856 (earlier it meant "thief," 1788, from family in a slang sense of "the fraternity of thieves"). Family tree "graph of ancestral relations" attested from 1752.

He was dressed in his best Coat, which had served him in the same Capacity before my Birth, and possibly, might be but little short in Antiquity, to the Root of his third Family Tree; and indeed, he made a venerable Figure in it. ["A Genuine Account of the Life and Transactions of Howell ap David Price, Gentleman of Wales," London, 1752]