Jamb shaft
A small shaft having a capital and a base, placed against the jamb of a door or window.
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved
jamb shaft
A small shaft having a capital and a base, placed against or forming part of the jamb of a door or window; occurs mostly in medieval architecture. (See illustration p. 552)
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.