英语词源字典 - 在线词源网站

latter (adj.)[latter 词源字典]: Old English lætra "slower," comparative of læt "late" (see late (adj.)). Sense of "second of two" first recorded 1550s. The modern later is a formation from mid-15c.[latter etymology, latter origin, 英语词源]
loo (n.2): type of card game, 1670s, short for lanterloo (1660s), from French lanturelu, originally (1620s) the refrain of a popular comic song; according to French sources the refrain expresses a mocking refusal or an evasive answer and was formed on the older word for a type of song chorus, turelure; apparently a jingling reduplication of loure "bagpipe" (perhaps from Latin lura "bag, purse").
From its primary signification -- a kind of bagpipe inflated from the mouth -- the word 'loure' came to mean an old dance, in slower rhythm than the gigue, generally in 6-4 time. As this was danced to the nasal tones of the 'loure,' the term 'loure' was gradually applied to any passage meant to be played in the style of the old bagpipe airs. ["Grove's Dictionary of Music and Musicians," London, 1906]
The refrain sometimes is met in English as turra-lurra.
retard (v.): late 15c., "make slow or slower," from French retarder "restrain, hold (someone) back, keep (someone from doing something); come to a stop" (13c.) or directly from Latin retardare "make slow, delay, keep back, hinder" (see retardation). Related: Retarded; retarding.

The noun is recorded from 1788 in the sense "retardation, delay;" from 1970 in offensive meaning "retarded person," originally American English, with accent on first syllable. Other words used for "one who is mentally retarded" include retardate (1956), retardee (1971).
retardation (n.): early 15c., "fact or action of making slower in movement or time," from Latin retardationem (nominative retardatio) "a delaying," noun of action from past participle stem of retardare "to make slow, delay, keep back, hinder," from re- (see re-), + tardare "to slow," related to tardus "slow, sluggish" (see tardy). Sense of "educational slowness" is from 1907.
sinister (adj.): early 15c., "prompted by malice or ill-will, intending to mislead," from Old French senestre, sinistre "contrary, false; unfavorable; to the left" (14c.), from Latin sinister "left, on the left side" (opposite of dexter), of uncertain origin. Perhaps meaning properly "the slower or weaker hand" [Tucker], but Klein and Buck suggest it's a euphemism (see left (adj.)) connected with the root of Sanskrit saniyan "more useful, more advantageous." With contrastive or comparative suffix -ter, as in dexter (see dexterity).

The Latin word was used in augury in the sense of "unlucky, unfavorable" (omens, especially bird flights, seen on the left hand were regarded as portending misfortune), and thus sinister acquired a sense of "harmful, unfavorable, adverse." This was from Greek influence, reflecting the early Greek practice of facing north when observing omens. In genuine Roman auspices, the augurs faced south and left was favorable. Thus sinister also retained a secondary sense in Latin of "favorable, auspicious, fortunate, lucky."

Meaning "evil" is from late 15c. Used in heraldry from 1560s to indicate "left, to the left." Bend (not "bar") sinister in heraldry indicates illegitimacy and preserves the literal sense of "on or from the left side" (though in heraldry this is from the view of the bearer of the shield, not the observer of it).
slow (v.): 1550s, "make slower;" 1590s, "go slower," from slow (adj.). Related: Slowed; slowing. Old English had slawian (intransitive) "to be or become slow, be sluggish," but the modern use appears to be a 16c. re-formation.
trot (n.): "a gait faster than a walk and slower than a run," c. 1300, originally of horses, from Old French trot "a trot, trotting" (12c.), from troter "to trot, to go," from Frankish *trotton, from Proto-Germanic *trott- (cognates: Old High German trotton "to tread"), derivative of *tred- (see tread (v.)). The trots "diarrhea" is recorded from 1808 (compare the runs).