Are yams and sweet potatoes the same?
1570s, "to corrupt, contaminate," also "to touch, tinge, imbue slightly" (1590s), from Middle English teynten "to convict, prove guilty" (late 14c.), partly from Old French ataint, past participle of ataindre "to touch upon, seize" (see attainder). Also 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.