Aster \As"ter\ ([a^]s"t[~e]r), n. [L. aster aster, star, Gr. 'asth`r star. See {Star}.] 1. (Bot.) A genus of herbs with compound white or bluish flowers; starwort; Michaelmas daisy. [1913 Webster] 2. (Floriculture) A plant of the genus {Callistephus}. Many varieties (called {China asters}, {German asters}, etc.) are cultivated for their handsome compound flowers. [1913 Webster] 3. (Biol.) A star-shaped figure of achromatic substance found chiefly in cells dividing by mitosis. [Webster 1913 Suppl.]