n. Olive-tree gum.n. In conchology: [capitalized] The typical genus of Olividæ, founded by Bruguière in 1789; the olives or olive-shells.n. Pl. olivas (-väz). Any species of Oliva; an olive-shell. See cut at olive-shell.n. Pl. olivæ (-vē). In anatomy, the olivary body of the brain.