thymus (n.)

plant of the mint family, noted for pungent aromatic quality and cultivated as a seasoning, c. 1300, time. thime, tyme, from Old French thym, tym (13c.), Anglo-French thime, time, and directly from Latin thymum, from Greek thymon.

This has been derived (Watkins) from PIE root *dheu- (1), base of words meaning "smoke," for its scent or from being burned as a sacrifice (compare Greek thymiao "fumigate," thymin "incense"), but Beekes finds this "doubtful" and suggests that "As a local plant name, the word is liable to be of Pre-Greek origin."

Generally tyme in 15c., for the restored spelling see th. Related: Thymic; thymy.

twentieth letter of the English alphabet; in the Phoenician alphabet the corresponding sign was the 22nd and last; all beyond T in the modern alphabet represents European alterations or additions. The sound has been consistent throughout its history. The letter formerly was branded on the hand of a convicted thief. Also compare th.

In Late Latin and Old French, -t- before -e- and -i- acquired the "s" value of -c- and words appeared in both spellings (nationem/nacionem) and often passed into Middle English with a -c- (nacioun). In most of these the spelling was restored to a -t- by or during early Modern English. Edmund Coote's "English Schoole-maister" (1596) still has malicious/malitious; and a few words well-established in the old spelling (space, place, coercion, suspicion) resisted restoration.

The pronunciation shift in -tu- words in southern English, to "-shu-" (nature, actually), was noticed by c. 1900.

To cross one's t's (and dot one's i's) "be exact" is attested from 1849. Phrase to a T "exactly, with utmost exactness" is recorded from 1690s, though the exact signification remains uncertain despite much speculation. The measuring tool called a T-square (sometimes suggested as the source of this) is recorded by that name only from 1785.

In medicine, the T-cell (1970) is so called because the cells are derived from the thymus. As a medieval numeral, T represented 160.

nitrogenous base, 1894, from German (Kossel and Neumann, 1893), from thymic acid, from which it was isolated, the acid so called because obtained from the thymus gland. With chemical suffix -ine (2).