Dictionary:

hygroscopic

  (hī'grə-skŏp'ĭk)

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Readily absorbing moisture, as from the atmosphere.

Readily absorbing water, as when table salt becomes damp. Materials such as calcium chloride and silica gel absorb water so readily that they are used as drying agents.

Having the property of absorbing moisture. When applied to gypsum products in contact with free water during their set, the resultant expansion is implied. See also expansion, hygroscopic.

Readily absorbing and retaining moisture from the air.

The quality of being hygroscopic.