Webster's Revised Unabridged Dictionary · 1913

Efflorescence

Efflorescence , noun

[French efflorescence.]

1.
(Botany) Flowering, or state of flowering; the blooming of flowers; blowth.
2.
(Medicine) A redness of the skin; eruption, as in rash, measles, smallpox, scarlatina, etc.
3.
(a) (Chemistry) The formation of the whitish powder or crust on the surface of efflorescing bodies, as salts, etc.
(b)
(Chemistry) The powder or crust thus formed.