Toothache \Tooth"ache`\, n. (Med.) Pain in a tooth or in the teeth; odontalgia. {Toothache grass} (Bot.), a kind of grass ({Ctenium Americanum}) having a very pungent taste. {Toothache tree}. (Bot.) (a) The prickly ash. (b) A shrub of the genus {Aralia} ({A. spinosa}).