The Collaborative International Dictionary of English v.0.48:
Sash \Sash\, n. [F. ch[^a]ssis a frame, sash, fr. ch[^a]sse a
shrine, reliquary, frame, L. capsa. See Case a box.]
1. The framing in which the panes of glass are set in a
glazed window or door, including the narrow bars between
2. In a sawmill, the rectangular frame in which the saw is
strained and by which it is carried up and down with a
reciprocating motion; -- also called gate.
French sash, a casement swinging on hinges; -- in
distinction from a vertical sash sliding up and down.