/ef'leuh res"/ , v.i. , effloresced, efflorescing .
1. to burst into bloom; blossom.
2. Chem.
a. to change either throughout or on the surface to a mealy or powdery substance upon exposure to air, as a crystalline substance through loss of water of crystallization.
b. to become incrusted or covered with crystals of salt or the like through evaporation or chemical change.
[ 1765-75; efflorescere to blossom out, equiv. to ef- EF- + florescere to begin to bloom ( flor ( i )-, s. of flos flower + -escere -ESCE) ]