Ef'flo-rēsce', v. i.
(ĕf'flo-rĕs'), v. i. [imp. & p. p. EFFLO-RESCED (-rĕst'); p. pr. & vb. n. EFFLORESCING.] [Lat. efflorescere, from ex, out, and flores-cere, to begin to blossom, v. incho. from florere, to blossom, from flos, a flower.]
Sense 1. (Chem.) To change over the surface, or throughout, to a whitish, mealy, or crystalline powder, from a gradual decomposition, on simple exposure to the air; as, Glauber's salts, and many others, effloresce.
Sense 2. To become covered with a whitish crust or light crystallization, from a slow chemical change between some of the ingredients of the matter covered and an acid proceeding commonly from an external source; as, the walls of limestone caverns sometimes effloresce with nitrate of lime in consequence of the action of nitric acid formed in the atmosphere. Dana.