Webster 1913 Edition



Flowering, or state of flowering; the blooming of flowers; blowth.
A redness of the skin; eruption, as in rash, measles, smallpox, scarlatina, etc.
The formation of the whitish powder or crust on the surface of efflorescing bodies, as salts, etc.
The powder or crust thus formed.

Webster 1828 Edition



In botany,the time of flowering; the season when a plant shows its first blossoms.
Among physicians, a redness of the skin; eruptions; as in rash, measles, small pox, scarlatina, &c.
In chimistry, the formation of small white threads, resembling the sublimated matter called flower, on the surface of certain bodies, as salts. This is properly a shooting out of minute spicular crystals, called sometimes a saline vegetation, as that of the sulphate of magnesia on the deserts of Siberia, and of natron in Egypt. In butter much salted, the salt shoots in spiculae, and an efflorescence is often seen on walls formed with plaster. In some species of salts, as in sulphate and carbonate of soda, the efflorescence consists of a fine white dust. This kind of efflorescence is the contrary of deliquescence. In the latter, the saline crystals decompose the air, or rather abstract moisture from it; in the former, the atmosphere decomposes the saline crystals, and the water of crystallization is abstracted from the salts.

Definition 2023





efflorescence (plural efflorescences)

  1. (chemistry) The formation of a powdery surface on crystals, as a hydrate is converted to anhydrous form by losing loosely bound water of crystallization to the atmosphere.
  2. (botany) The production of flowers.
  3. (construction) An encrustation of soluble salts, commonly white, deposited on the surface of stone, brick, plaster, or mortar; usually caused by free alkalies leached from mortar or adjacent concrete as moisture moves through it.
  4. (geology) An encrustation of soluble salts, deposited on rock or soil by evaporation; often found in arid or geothermal environments.
  5. (metaphorical) Rapid flowering of a culture or civilisation etc.
  6. (pathology) A redness, rash, or eruption on the skin.

Derived terms