stile
One of the main members of a millwork frame to which the others are attached, especially by mortise and tenon, such as the vertical framing members at the edge of a window sash or paneled door; may be horizontal in wall paneling; types include diminished stile, gunstock stile, hanging stile, meeting stile, pulley stile, shutting stile. See also rail montant. Photo from Metuchen, New Jersey, 2019. 2. Any plane surface forming a border. 3. A fence post that supports rails. 4. A stair with steep steps on both sides of a fence or wall. (Bucher, 1996)