Online Etymology Dictionary

awhile (adv.): Old English ane hwile "(for) a while" (see while (n.)); usually written as one word since 13c.
spat (n.1): "petty quarrel," 1804, American English, of unknown origin; perhaps somehow imitative (compare spat "smack, slap," attested from 1823).
Spandex (n.): synthetic fiber, 1959, American English, proprietary name, an arbitrary formation from expand + commercial suffix -ex.
stent (n.): "tube implanted temporarily," 1964, named for Charles T. Stent (1807-1885), English dentist.
sitz-bath (n.): 1849, a hybrid, from German Sitzbad, literally "bath in a sitting position," with English bath for German Bad.
smack (n.4): "heroin," 1942, American English slang, probably an alteration of schmeck "a drug," especially heroin (1932), from Yiddish schmeck "a sniff."
souter (n.): "maker or mender of shoes," Old English sutere, from Latin sutor "shoemaker," from suere "to sew, stitch" (see sew).
thereafter (adv.): Old English þær æfter; see there + after. Similar formation in Dutch daarachter, Swedish derefter.
thereof (adv.): "of that, of it," Old English þærof; see there + of. Similar formation in Swedish, Danish deraf.
thereon (adv.): Old English þæron; see there + on. Similar formation in German daran.
thereunder (adv.): Old English þærunder; see there + under. Similar formation in Old Frisian therunder, German darunter.
throughout (prep.): late Old English þurhut; see through + out (adv.). Similar formation in German durchaus.
tighten (v.): "to make tight," 1727; the earlier verb was simply tight, from Old English tyhtan, from the root of tight. Related: Tightened; tightening.
told: past tense and past participle of tell (v.), from Old English tealde, past tense of tellan.
took: past tense of take (v.), from late Old English toc, past tense of tacan.
wrong (n.): "that which is improper or unjust," late Old English, from wrong (adj.). Meaning "an unjust action" is recorded from c. 1200.
colour: chiefly British English spelling of color (q.v.); for ending see -or. Related: Coloured; colouring; colourful; colours.
honour: chiefly British English spelling of honor; also see -or. Related: Honoured; honouring; honours.
humour: chiefly British English spelling of humor; see -or. Related: Humourous; humourously; humourist; humourless, etc.
favour: chiefly British English spelling of favor (q.v.); for spelling, see -or. Related: Favourite; favouritism.
within (adv., prep.): Old English wiðinnan "within, from within," literally "against the inside," see with + in.
tchotchke (n.): "trinket, gewgaw," also (transferred) "pretty girl," 1964, American English, from Yiddish, from a Slavic source (compare Russian tsatska).
wreathe (v.): 1520s (transitive), a back-formation from wrethen, Middle English past participle of writhe. Intransitive sense from 1580s. Related: Wreathed; wreathing.
walkabout (n.): "periodic migration by a westernized Aboriginal into the bush," 1828, Australian English, from walk (v.) + about.
yclept: Old English gicliopad; from y- + past participle of cleopian, cpipian "to speak, call; summon, invoke; implore" (see clepe).
upchuck (v.): "to vomit," by 1960, American English slang, from up (adv.) + chuck (v.) "to throw."
twister (n.): late 15c., "one who spins thread," agent noun from twist (v.). Meaning "tornado" is attested from 1881, American English.
underclassman (n.): "sophomore or freshman," 1869, American English, from under (adj.) + class (n.) in the school form sense + man (n.).
understanding (n.): Old English understanding "comprehension," verbal noun from understand (v.). Meaning "mutual agreement" is attested from 1803.
underling (n.): late Old English, "one who owes allegiance to a sovereign or ruler," from under + diminutive suffix -ling.
unfasten (v.): early 13c., from un- (2) "opposite of" + fasten. Old English had unfæstnian "to unfasten." Related: Unfastened; unfastening.
untie (v.): Old English untigan "loosen, unchain," from un- (2) "opposite of" + tie (v.). Related: Untied; untying.
savour: chiefly British English spelling of savor (q.v.); for spelling, see -or. Related: Savoured; savouring.
ach (interj.): aspirated form of ah; in English often used to represent German or Celtic speech.
advantageous (adj.): 1590s, formed in English from advantage, or else from French avantageux (15c.), from avantage (see advantage). Related: Advantageously; advantageousness.
anywise (adv.): Old English ænige wisan, from any + wise (n.). One-word form from c. 1200.
ascendance (n.): 1742, from ascend + -ance. Properly "the act of ascending," but used from the start in English as a synonym of ascendancy.
amortise (v.): chiefly British English spelling of amortize; for suffix, see -ize. Related: Amortised; amortising.
clamour: chiefly British English spelling of clamor (q.v.); for spelling, see -or. Related: Clamoured; clamouring; clamourous.
A.A.A.: also AAA, abbreviation of American Automobile Association, attested 1902, American English, the year the organization was founded.
apologise (v.): chiefly British English spelling of apologize; for suffix, see -ize. Related: Apologised; apologising.
recognise (v.): chiefly British English spelling of recognize; for spelling, see -ize. Related: Recognised; recognising; recognisance.
emphasise (v.): chiefly British English spelling of emphasize; for spelling, see -ize. Related: Emphasised; emphasising.
empathise (v.): chiefly British English spelling of empathize; for suffix, see -ize. Related: Empathised; empathising.
realise (v.): chiefly British English spelling of realize; for suffix, see -ize. Related: Realisation; realised; realising.
anticyclone (n.): 1863, coined by Francis Galton (1822-1911), English polymath, explorer, and meteorologist, from anti- + cyclone. Related: Anticyclonic.
still (n.1): "distilling apparatus," 1530s, from Middle English stillen "to distill" (c. 1300), a variant of distillen (see distill).
swollen (adj.): early 14c., past participle adjective from strong conjugation of swell (v.); from Old English geswollen, past participle of swellan.
shay (n.): 1717, back-formation from chaise (q.v.), wrangled into English and mistaken for a plural.
sliver (n.): "splinter of wood," late 14c., from obsolete verb sliven "to split, cleave," from Old English toslifan "to split, cleave" (see sleave).