noun a genus of herbs with compound white or bluish flowers; starwort; michaelmas daisy.
2. aster ·add. ·noun a star-shaped figure of achromatic substance found chiefly in cells dividing by mitosis.
3. aster ·noun a plant of the genus callistephus. many varieties (called china asters, german asters, ·etc.) are cultivated for their handsome compound flowers.