Theriac \The"ri*ac\, Theriaca \The*ri"a*ca\, n. [L. theriaca an antidote against the bite of serpents, Gr. ?: cf. F. th['e]riaque. See Treacle.]

1. (Old Med.) An ancient composition esteemed efficacious against the effects of poison; especially, a certain compound of sixty-four drugs, prepared, pulverized, and reduced by means of honey to an electuary; -- called also theriaca Andromachi, and Venice treacle.

2. Treacle; molasses. --British Pharm.

Source: Webster's Revised Unabridged Dictionary (1913)