casement Meaning, Definition & Usage

  1. noun a window sash that is hinged (usually on one side)

WordNet

Case"ment noun
Etymology
Shortened fr. encasement. See Incase 1st Case, and cf. Incasement.
Definitions
  1. (Arch.) A window sash opening on hinges affixed to the upright side of the frame into which it is fitted. (Poetically) A window.
    A casement of the great chamber window. Shak.

Webster 1913