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A deep block sometimes placed above a Byzantine capital to support the wide voissoirs of an arch above; also, an isolated section of an entablature above a column.
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved
A member or supplementary capital resting on the top of the capital of a column; see impost block; also called a double capital.
impost block, dosseret, supercapital
A transitional member, often tapered, placed above a column capital to receive the thrust of vaults or arches.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.