v.intr. 1 burst out into flower. 2 Chem. a (of a substance) turn to a fine powder on exposure to air. b (of salts) come to the surface and crystallize on it. c (of a surface) become covered with salt particles. efflorescence n. efflorescent adj.
[ L efflorescere (as EX-(1), florere to bloom f. flos floris flower) ]