1) Projecting room on an upper floor (in the medieval sense; later an upper-floor bay window).
(Gies, Joseph and Francis. Life in a Medieval Castle, 226)
2) Originally a projection or built-out gallery, often a porch outside an upper entrance reached by an external staircase, later a projection usually containing a window. Now chiefly used for a window corbelled out from an upper storey.
(Wood, Margaret. The English Medieval House, 413)
*term definitions retrieved from Netserf’s Medieval Glossary