c.1400, from Latin tinctura "act of dyeing or tingeing," from tinctus "dye," past participle of tingere "to tinge, dye, moisten, soak," from PIE root *teng- "to soak" (cf. Old High German dunkon "to soak," Greek tengein "to moisten"). Meaning "solution of medicine in a mixture of alcohol" is first recorded 1640s. The verb is recorded from 1610s.
tincture tinc·ture (tĭngk'chər)
A coloring or dyeing substance.
Abbr. tinct, tr An alcohol solution of a nonvolatile medicine.