A large polygonal recess with a window, projecting from a building, usually at an upper storey, and supported from the ground or on corbels. Also…

‘A window forming a bay or recess in a room, and projecting outwards from the wall, either in a rectangular, polygonal, or semicircular form…

compassed roof, compassed window: see compass-window n. at compass, n.1 adj.adv. compounds 2.

Hollow. literal and figurative. boss window: bay window.

a semicircular bay window (cf. compassed, adj. 3b).

A jutting or projecting window; a bay window.

A bay window segmentally curved on plan; called in A.P.S. Dict. Arch., a Bow Bay-window.

the window of an oriel; a bay window projecting from an upper storey.

(see quot.).

Architecture. Short for bow window, n.