Sash, n. [F. châssis a frame, sash, fr. châsse 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 the panes.
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.