Noah Webster's Dictionary 1. (n.) The vertical side of any opening, as a door or fireplace; hence, less properly, any narrow vertical surface of wall, as the of a chimney-breast or of a pier, as distinguished from its face. 2. (n.) Any thick mass of rock which prevents miners from following the lode or vein. 3. (v. t.) See Jam.

Multi-Version Concordance Jamb (1 Occurrence) Ezekiel 40:6 Then came he unto the gate which looketh toward the east, and went up the steps thereof: and he measured the threshold of the gate, one reed broad; and the other threshold, one reed broad. (See JPS)