c. 1300, from Anglo-French tailour, Old French tailleor "tailor," also "stone-mason" (13c., Modern French tailleur), literally "a cutter," from tailler "to cut," from Late Latin or old Medieval Latin taliare "to split" (compare Medieval Latin taliator vestium "a cutter of clothes"), from Latin talea "a slender stick, rod, staff; a cutting, twig."

Although historically the tailor is the cutter, in the trade the 'tailor' is the man who sews or makes up what the 'cutter' has shaped. [OED]

The post-Latin sense development would be "piece of a plant cut for grafting," hence a verb, "cut a shoot," then, generally, "to cut." Possible cognates include Sanskrit talah "wine palm," Old Lithuanian talokas "a young girl," Greek talis "a marriageable girl" (for sense, compare slip of a girl, twiggy), Etruscan Tholna, name of the goddess of youth.

Kent. ... You cowardly rascal, nature disclaims in thee; a tailor made thee.

Corn. Thou art a strange fellow: a tailor make a man?

Kent. Ay, a tailor, sir: a stone cutter, or a painter, could not have made him so ill, though they had been but two hours at the trade.

["King Lear"]

One who makes outer garments to order, as opposed to a clothier, who makes them for sale ready-made. Tailor-made first recorded 1832 (in a figurative sense); literal sense was "heavy and plain, with attention to exact fit and with little ornamentation," as of women's garments made by a tailor rather than a dress-maker.

1570s, "to corrupt, contaminate," also "to touch, tinge, imbue slightly" (1590s), from Middle English teynten "to convict, prove guilty" (late 14c.), which is partly from Old French ataint, past participle of ataindre "to touch upon, seize" (see attainder). It also is from Anglo-French teinter "to color, dye" (early 15c.), from Old French teint (12c.), past participle of teindre "to dye, color," from Latin tingere (see tincture). Related: Tainted; tainting.

also 'taint, representing a colloquial contraction of it ain't, by 1830s, American English. The joke about the perineum involving this word dates to at least 1977.

mausoleum at Agra, India, built by Shah Jahan for his favorite wife, from Persian, perhaps "the best of buildings," with second element, mahal, from Urdu mahall "private apartments; summer house or palace," from Arabic halla "to lodge." But some authorities hold that the name of the mausoleum is a corruption of the name of the woman interred in it, Mumtaz (in Persian, literally "chosen one") Mahal, who died in 1631. Persian taj is literally "crown, diadem, ornamental headdress," but here denoting an object of distinguished excellence. Figurative use of Taj Mahal in English as a name denoting anything surpassing or excellent is attested from 1895.