Online Etymology Dictionary

weight (v.): "to load with weight," 1747 (figuratively, of the mind, from 1640s), from weight (n.). Of horses in a handicap race, 1846. Sense in statistics is recorded from 1901. Related: Weighted; weighting.
weightage (n.): 1893, from weight (n.) + -age.
weightless (adj.): "having no weight," 1540s, from weight (n.) + -less. Related: Weightlessly; weightlessness (1867).
weighty (adj.): late 14c., "heavy;" late 15c., "important, serious, grave;" from weight (n.) + -y (2). Related: Weightiness.
Weimar (adj.): in reference to the pre-1933 democratic government of Germany, 1932, from name of city in Thuringia where German constitution was drawn up in 1919. The place name is a compound of Old High German wih "holy" + mari "lake" (see mere (n.)).
Weimaraner (n.): dog breed, 1943, from Weimar, german city, + German suffix -aner indicating "of this place." Originally bred as a hunting dog in the Weimar region.
weir (n.): Old English wer "dam, fence, enclosure," especially one for catching fish (related to werian "dam up"), from Proto-Germanic *wer-jon- (source also of Old Norse ver, Old Frisian and Middle Dutch were, Dutch weer, Old High German wari, German Wehr "defense, protection," Gothic warjan "to defend, protect"), from PIE *wer- (5) "to cover, shut" (source also of Sanskrit vatah "enclosure," vrnoti "covers, wraps, shuts;" Lithuanian užveriu "to shut, to close;" Old Persian *pari-varaka "protective;" Latin (op)erire "to cover," (ap)erire "open, uncover" (with ap- "off, away"); Old Church Slavonic vora "sealed, closed," vreti "shut;" Old Irish feronn "field," properly "enclosed land").
weird (adj.): c. 1400, "having power to control fate, from wierd (n.), from Old English wyrd "fate, chance, fortune; destiny; the Fates," literally "that which comes," from Proto-Germanic *wurthiz (source also of Old Saxon wurd, Old High German wurt "fate," Old Norse urðr "fate, one of the three Norns"), from PIE *wert- "to turn, to wind," (source also of German werden, Old English weorðan "to become"), from root *wer- (3) "to turn, bend" (see versus). For sense development from "turning" to "becoming," compare phrase turn into "become."

The sense "uncanny, supernatural" developed from Middle English use of weird sisters for the three fates or Norns (in Germanic mythology), the goddesses who controlled human destiny. They were portrayed as odd or frightening in appearance, as in "Macbeth" (and especially in 18th and 19th century productions of it), which led to the adjectival meaning "odd-looking, uncanny" (1815); "odd, strange, disturbingly different" (1820). Related: Weirdly; weirdness.
weirdo (n.): "strange person," 1955, from weird. Compare earlier Scottish weirdie "young man with long hair and a beard" (1894).
welch (v.): 1857, racing slang, "to refuse or avoid payment of money laid as a bet," probably a disparaging use of the national name Welsh. Related: Welched; welching.
welcome (n.): Old English wilcuma "welcome!" exclamation of kindly greeting, from earlier wilcuma (n.) "welcome guest," literally "one whose coming suits another's will or wish," from willa "pleasure, desire, choice" (see will (n.)) + cuma "guest," related to cuman (see come). Similar formation in Old High German willicomo, Middle Dutch wellecome. Meaning "entertainment or public reception as a greeting" is recorded from 1530. The adjective is from Old English wilcuma. You're welcome as a formulaic response to thank you is attested from 1907. Welcome mat is from 1908; welcome wagon is attested from 1940.
welcome (v.): Old English wilcumian "to welcome, greet gladly," from wilcuma (see welcome (n.)). Related: Welcomed; welcoming.
weld (v.): 1590s, "unite or consolidate by hammering or compression, often after softening by heating," alteration of well (v.) "to boil, rise;" influenced by past participle form welled. Related: Welded; welding.
weld (n.1): plant (Resedo luteola) producing yellow dye, late 14c., from Old English *wealde, perhaps a variant of Old English wald "forest" (see wold). Spanish gualda, French gaude are Germanic loan-words.
weld (n.2): "joint formed by welding," 1831, from weld (v.).
welder (n.): 1828, agent noun from weld (v.).
welfare (n.): c. 1300, from Old English wel faran "condition of being or doing well," from wel (see well (adv.)) + faran "get along" (see fare (v.)). Similar formation in Old Norse velferð. Meaning "social concern for the well-being of children, the unemployed, etc." is first attested 1904; meaning "organized effort to provide for maintenance of members of a group" is from 1918. Welfare state is recorded from 1941.
welkin (n.): "sky" (poetic), Old English wolcen "cloud," also "sky, heavens," from Proto-Germanic *welk- (source also of Old Saxon wolkan, Old Frisian wolken, Middle Dutch wolke, Dutch wolk, Old High German wolka, German Wolke "cloud," from PIE *welg- "wet" (source also of Lithuanian vilgyti "to moisten," Old Church Slavonic vlaga "moisture," Czech vlhky "damp").
well (adv.): "in a satisfactory manner," Old English wel "abundantly, very, very much; indeed, to be sure; with good reason; nearly, for the most part," from Proto-Germanic *welo- (source also of Old Saxon wela, Old Norse vel, Old Frisian wel, Dutch wel, Old High German wela, German wohl, Gothic waila "well"), from PIE root *wel- (2) "to wish, will" (source also of Sanskrit prati varam "at will," Old Church Slavonic vole "well," Welsh gwell "better," Latin velle "to wish, will," Old English willan "to wish;" see will (v.)).

Also used in Old English as an interjection and an expression of surprise. The adjective was in Old English in the sense "in good fortune, happy," from the adverb; sense of "satisfactory" is from late 14c.; "agreeable to wish or desire" is from mid-15c.; "in good health, not ailing" is from 1550s. Well-to-do "prosperous" is recorded from 1825.
well (v.): "to spring, rise, gush," Old English wiellan (Anglian wællan), causative of weallan "to boil, bubble up, rise (in reference to a river)" (class VII strong verb; past tense weoll, past participle weallen), from Proto-Germanic *wall- "roll" (source also of Old Saxon wallan, Old Norse vella, Old Frisian walla, Old High German wallan, German wallen, Gothic wulan "to bubble, boil"), from PIE root *wel- (3) "to turn, roll" (see volvox), on notion of "roiling or bubbling water."
well (n.): "hole dug for water, spring of water," Old English wielle (West Saxon), welle (Anglian) "spring of water, fountain," from wiellan (see well (v.)). "As soon as a spring begins to be utilized as a source of water-supply it is more or less thoroughly transformed into a well" [Century Dictionary]. Figurative sense of "source from which anything is drawn" was in Old English.
well-acquainted (adj.): 1728, "having good acquaintance with," from well (adv.) + acquainted.
well-adjusted (adj.): 1735, in reference to mechanisms, etc., from well (adv.) + past participle of adjust (v.). In reference to emotional balance, recorded from 1959.
well-balanced (adj.): 1620s, from well (adv.) + past participle of balance (v.).
well-behaved (adj.): 1590s, from well (adv.) + past participle of behave (v.).
well-being (n.): 1610s, from well (adv.) + gerundive of be.
well-beloved (adj.): late 14c., from well (adv.) + beloved.
well-born (adj.): Old English welboren; see well (adv.) + born.
well-bred (adj.): 1590s, from well (adv.) + bred.
well-done (adj.): c. 1200, "wise, prudent," from well (adv.) + done. Meaning "thoroughly cooked," in reference to meat, is attested from 1747. Well done! as an exclamation of approval is recorded from mid-15c.
well-earned (adj.): 1730, from well (adv.) + past participle of earn (v.).
well-endowed (adj.): 1680s, "with ample material endowments," from well (adv.) + past participle of endow (v.). Sexual sense is attested from 1951. A Middle English term for "naturally well-endowed" was furnished in nature.
well-fed (adj.): mid-14c., from well (adv.) + past participle of feed (v.).
well-founded (adj.): late 14c., from well (adv.) + past participle of found (v.1).
well-heeled (adj.): "well-off, having much money, in good circumstances;" also "well-equipped," 1872, American English slang (originally in the "money" sense), from well (adv.) + colloquial sense of heeled. "[A]pplied to a player at cards who has a good hand, to a person who possesses plenty of money, or to a man who is well armed" [Century Dictionary]. From 1817 in a literal sense, in reference to shoes.
well-hung (adj.): 1610s, in male genital sense, from well (adv.) + hung (adj.).
well-informed (adj.): mid-15c., from well (adv.) + past participle of inform (v.).
well-intentioned (adj.): 1590s, from well (adv.) + intentioned "having intentions" (of a specified kind).
well-kept (adj.): c. 1400, from well (adv.) + past participle of keep (v.).
well-known (adj.): late 15c., from well (adv.) + past participle of know (v.).
well-mannered (adj.): late 14c., "moral, virtuous," from well (adv.) + mannered. Meaning "with good manners" is from 1540s.
well-meaning (adj.): late 14c., from well (adv.) + present participle of mean (v.).
well-meant (adj.): late 15c., from well (adv.) + past participle of mean (v.).
well-nigh (adv.): Old English wel neah, from well (adv.) + nigh.
well-off (adj.): 1733, "comfortable," from well (adv.) + off. Meaning "prosperous, not poor" is recorded from 1849.
well-ordered (adj.): c. 1600, from well (adv.) + past participle of order (v.).
well-read (adj.): 1590s, from well (adv.) + read (adj.).
well-regulated (adj.): 1709 (Shaftsbury), from well (adv.) + past participle of regulate (v.).
well-respected (adj.): 1590s, from well (adv.) + past participle of respect (v.).
well-rounded (adj.): 1796, "symmetrically proportioned, complete in all parts," from well (adv.) + past participle of round (v.). Figurative sense is from mid-19c.