Vaccine \Vac"cine\, a. [L. vaccinus, fr. vacca a cow; cf. Skr. v[=a]c to bellow, to groan.]

Of or pertaining to cows; pertaining to, derived from, or caused by, vaccinia; as, vaccine virus; the vaccine disease. -- n. The virus of vaccinia used in vaccination.

Source: Webster's Revised Unabridged Dictionary (1913)