ASHLAR, also written ASHLER, ASHELERE, in archi tecture, squared stone used for facing walls ; also as an adjective, of a wall built of squared stones. Sometimes the word is used of any stone wall facing which is worked or tooled, whether squared or not, but such work is usually known as "rough" or "uncoursed" ashlar. An ashlar piece in English carpentry is a vertical timber inserted between the rafters and the wall plate. (See CARPENTRY.)