Mortise \Mor"tise\, v. t. [imp. & p. p. {Mortised}; p. pr. & vb. n. {Mortising}.] 1. To cut or make a mortise in. [1913 Webster] 2. To join or fasten by a tenon and mortise; as, to mortise a beam into a post, or a joist into a girder. [1913 Webster]