1. mortise - Noun
2. mortise - Verb
A cavity cut into a piece of timber, or other material, to receive something (as the end of another piece) made to fit it, and called a tenon.
To cut or make a mortisein.
To join or fasten by a tenon and mortise; as, to mortise a beam into a post, or a joist into a girder.
Source: Webster's dictionaryEarly Egyptians also knew how to fasten the planks of this ship together with mortise and tenon joints. Source: Internet
Other necks are built separately and joined to the body either with a dovetail joint, mortise or flush joint. Source: Internet