Online Etymology Dictionary

waterlog (v.): 1779, from water (n.1) + log (n.); the notion is of "reduce to a log-like condition."
Waterloo (n.): battle took place June 18, 1815, at village near Brussels; extended sense of "a final, crushing defeat" is first attested 1816 in letter of Lord Byron. The second element in the place name is from Flemish loo "sacred wood."
watermark (n.): 1708, "distinctive mark on paper," from water (n.1) + mark (n.1). Cf. German wassermarke. Not produced by water, but probably so called because it looks like a wet spot. The verb is recorded from 1866.
watermelon (n.): 1610s, from water (n.1) + melon. So called for being full of thin juice. Cf. French melon d'eau.
waterproof (adj.): 1725, from water (n.1) + proof. The verb is first recorded 1843. Related: Waterproofed; waterproofing.
watershed (n.): "line separating waters flowing into different rivers," 1803, from water (n.1) + shed. A loan-translation of German Wasser-scheide. Figurative sense is attested from 1878. Meaning "ground of a river system" is from 1878.
waterspout (n.): late 14c., "drainpipe," from water (n.1) + spout (n.). Meaning "whirlwind on open water" is recorded from 1738.
watertight (adj.): late 14c., from water (n.1) + tight. Figurative use from 1640s.
waterway (n.): Old English wæterweg; see water (n.1) + way.
watery (adj.): Old English wæterig; see water (n.1) + -y (2).
watt (n.): unit of electrical power, 1882, in honor of James Watt (1736-1819), Scottish engineer and inventor.
wattage (n.): 1903, from watt + -age.
wattle (n.2): "fleshy appendage below the neck of certain birds," 1510s (extended jocularly to human beings, 1560s), of uncertain origin and of doubtful relationship to wattle (n.1).
wattle (n.1): "stakes interlaced with twigs and forming the framework of the wall of a building," Old English watol "hurdle," in plural "twigs, thatching, tiles," related to weðel "bandage," of unknown origin. Surviving in wattle-and-daub "building material for huts, etc." (1808).
Watusi (n.): racial group in Rwanda and Burundi (also called Tutsi), 1899. As the name of a popular dance, attested from 1964.
wave (v.): "move back and forth," Old English wafian "to wave with the hands" (related to wæfre "wavering, restless"), from Proto-Germanic *wab- (cf. Old Norse vafra "to hover about," Middle High German waben "to wave, undulate"), possibly from PIE root *webh- "to move to and fro; to weave" (see weave (v.)). Meaning "to make a sign by a wave of the hand" is from 1510s. Related: Waved; waving.
I was much further out than you thought
And not waving but drowning.
[Stevie Smith]
wave (n.): "moving billow of water," 1520s, from wave (v.), replacing Middle English waw, which is from Old English wagian "to move to and fro" (cf. Old Saxon, Old High German wag, Old Frisian weg, Old Norse vagr "water in motion, wave, billow," Gothic wegs "tempest;" see wag (v.)). The usual Old English word for "moving billow of water" was yð.

The "hand motion" meaning is recorded from 1680s; meaning "undulating line" is recorded from 1660s. Of people in masses, first recorded 1852; in physics, from 1832. Sense in heat wave is from 1843. The crowd stunt in stadiums is attested under this name from 1984, the thing itself said to have been done first Oct. 15, 1981, at the Yankees-A's AL championship series game in the Oakland Coliseum; soon picked up and popularized at University of Washington. To make waves "cause trouble" is attested from 1962.
wavelength (n.): 1850, "distance between peaks of a wave," from wave (n.) + length. Originally of spectra; radio sense is attested by 1925. Figurative sense of "mental harmony" is recorded from 1927, on analogy of radio waves.
wavelet (n.): 1813, diminutive of wave (n.).
waver (v.): late 13c., weyveren, "to show indecision," probably related to Old English wæfre "restless, wavering," from Proto-Germanic *wæbraz (cf. Middle High German wabern "to waver," Old Norse vafra "to hover about"), a frequentative form from the root of wave (v.). Related: Wavered; wavering.
wavy (adj.): 1580s, from wave (n.) + -y (2).
wax (n.): "substance made by bees," Old English weax, from Proto-Germanic *wakhsan (cf. Old Saxon, Old High German wahs, Old Norse vax, Dutch was, German Wachs); cognate with Old Church Slavonic vasku, Lithuanian vaškas, Polish wosk, Russian vosk "wax" (but these may be from Germanic). Waxworks "exhibition of wax figures representing famous or notorious persons" first recorded 1796.
wax (v.): "grow bigger or greater," Old English weaxan "to increase, grow" (class VII strong verb; past tense weox, past participle weaxen), from Proto-Germanic *wakhsan (cf. Old Saxon, Old High German wahsan, Old Norse vaxa, Old Frisian waxa, Dutch wassen, German wachsen, Gothic wahsjan "to grow, increase"), from PIE *wegs- (cf. Sanskrit vaksayati "cause to grow," Greek auxein "to increase"), extended form of root *aug- "to increase" (see augment). Strong conjugation archaic after 14c. Related: Waxed; waxing.
waxwing (n.): 1817, from wax (n.) + wing (n.). So called for appendages at the tips of its feathers which look like red sealing-wax.
waxy (adj.): 1550s, "made of wax," from wax (n.) + -y (2). Figurative use from 1590s. Meaning "like wax" is from 1799. Related: Waxiness.
way (n.): Old English weg "road, path, course of travel," from Proto-Germanic *wegaz (cf. Old Saxon, Dutch weg, Old Norse vegr, Old Frisian wei, Old High German weg, German Weg, Gothic wigs "way"), from PIE *wegh- "to move" (see weigh). Most of the extended senses developed in Middle English. Adverbial meaning "very, extremely" is by 1986, perhaps from phrase all the way. Ways and means "resources at a person's disposal" is attested from early 15c. Way-out (adj.) "original, bold," is jazz slang, first recorded 1940s. Encouragement phrase way to go is short for that's the way to go.
wayfarer (n.): mid-15c., agent noun from way + fare (v.). Earlier was wayferer (late 14c.). The brand of sunglasses (manufactured by Ray-Ban) dates to 1952.
wayfaring (n.): Old English wegfarende; see way + fare (v.).
waylay (v.): "to ambush," 1510s, from way + lay (v.), on model of Middle Low German, Middle Dutch wegelagen "besetting of ways, lying in wait with evil or hostile intent along public ways."
Wayne: surname, by 1319, variant of Wain, representing wainwright, wainer (see wain) or perhaps "one who dwells by the tavern with the sign of the wain."
wayside (n.): "the side of the road," c.1400, from way + side (n.). To fall by the wayside is from Luke viii:5.
wayward (adj.): late 14c., shortening of aweiward "turned away," from away + -ward.
we (pron.): Old English we, from Proto-Germanic *wiz (cf. Old Saxon wi, Old Norse ver, Danish vi, Old Frisian wi, Dutch wij, Old High German and German wir, Gothic weis "we"), from PIE *wei- (cf. Sanskrit vayam, Old Persian vayam, Hittite wesh "we," Old Church Slavonic ve "we two," Lithuanian vedu "we two").

The "royal we" (use of plural pronoun to denote oneself) is at least as old as "Beowulf" (c.725); use by writers to establish an impersonal style is also from Old English; it was especially common 19c. in unsigned editorials, to suggest staff consensus, and was lampooned as such since at least 1853 (cf. also wegotism).
weak (adj.): c.1300, from Old Norse veikr "weak," cognate with Old English wac "weak, pliant, soft," from Proto-Germanic *waikwaz "yield," *wikanan "bend" (cf. Old Saxon wek, Swedish vek, Middle Dutch weec, Dutch week "weak, soft, tender," Old High German weih "yielding, soft," German weich "soft," from PIE root *weik- "to bend, wind" (see vicarious). Sense of "lacking authority" is first recorded early 15c.; that of "lacking moral strength" late 14c. Weak-kneed "wanting in resolve" is from 1870.
weaken (v.): 1520s, from weak + -en (1). The earlier verb was simply weak (late 14c.). Related: Weakened; weakening.
weakfish (n.): 1838, from Dutch weekvisch, from week "soft" (see weak).
weakling (n.): 1520s, coined by Tyndale from weak as a loan-translation of Luther's Weichling "effeminate man," from German weich "soft" (see weak).
weakness (n.): c.1300, "quality of being weak," from weak + -ness. Meaning "a disadvantage, vulnerability" is from 1590s. That of "self-indulgent fondness" is from 1712; meaning "thing for which one has an indulgent fondness" is from 1822.
weal (n.1): "well-being," Old English wela "wealth," in late Old English also "welfare, well-being," from West Germanic *welon, from PIE root *wel- "to wish, will" (see will (v.)). Related to well (adv.).
weal (n.2): "raised mark on skin," 1821, alteration of wale (q.v.).
weald (n.): Old English (West Saxon) weald "forest, woodland," specifically the forest between the North and South Downs in Sussex, Kent, and Surrey; a West Saxon variant of Anglian wald (see wold).
wealth (n.): mid-13c., "happiness," also "prosperity in abundance of possessions or riches," from Middle English wele "well-being" (see weal (n.1)) on analogy of health.
wealthy (adj.): late 14c., from wealth + -y (2). Meaning "wealthy persons collectively" is from late 14c.
wean (v.): Old English wenian "to accustom," from Proto-Germanic *wanjanan (cf. Old Norse venja, Dutch wennen, Old High German giwennan, German gewöhnen "to accustom"), from *wanaz "accustomed" (related to wont). The sense of weaning a child from the breast in Old English was generally expressed by gewenian or awenian, which has a sense of "unaccustom" (cf. German abgewöhnen, entwöhnen "to wean," literally "to unaccustom"). The prefix subsequently wore off. Figurative extension to any pursuit or habit is from 1520s.
weapon (n.): Old English wæpen "instrument of fighting and defense," from Proto-Germanic *wæpnan (cf. Old Saxon wapan, Old Norse vapn, Danish vaaben, Old Frisian wepin, Middle Dutch wapen, Old High German waffen, German wafen (neuter), waffe (fem.)), from *webno-m, of unknown origin with no cognates outside Germanic.
weaponry (n.): 1844, from weapon + -ry.
weapons of mass destruction (n.): "nuclear, biological and chemical weapons" attested by 1946, apparently first used (in Russian) by the Soviets.
The terms "weapons of mass destruction" and "WMD" mean chemical, biological, and nuclear weapons, and chemical, biological, and nuclear materials used in the manufacture of such weapons. [United States Code: Title 50, "War and National Defense," chapter 43, Â§ 2902, 2009]
wear (v.): Old English werian "to clothe, put on," from Proto-Germanic *wazjanan (cf. Old Norse verja, Old High German werian, Gothic gawasjan "to clothe"), from PIE *wes- "to clothe" (cf. Sanskrit vaste "he puts on," vasanam "garment;" Avestan vah-; Greek esthes "clothing," hennymi "to clothe," eima "garment;" Latin vestire "to clothe;" Welsh gwisgo, Breton gwiska; Old English wæstling "sheet, blanket;" Hittite washshush "garments," washanzi "they dress").

The Germanic forms "were homonyms of the vb. for 'prevent, ward off, protect' (Goth. warjan, O.E. werian, etc.), and this was prob. a factor in their early displacement in most of the Gmc. languages" [Buck]. Shifted from a weak verb (past tense and past participle wered) to a strong one (past tense wore, past participle worn) in 14c. on analogy of rhyming strong verbs such as bear and tear.

Secondary sense of "use up, gradually damage" (late 13c.) is from effect of continued use on clothes. To be the worse for wear is attested from 1782; noun phrase wear and tear is first recorded 1660s.
wear (n.): "action of wearing" (clothes), mid-15c., from wear (v.). Meaning "what one wears" is 1570s. To be the worse for wear is attested from 1782; noun phrase wear and tear is first recorded 1660s, implying the sense "process of being degraded by use."
wearisome (adj.): mid-15c., "weary," also "causing weariness," from weary + -some.