A lot vs. Alot: 9 Grammatical Pitfalls
c.1400, "hole or groove in which something is fitted to form a joint," from Old French mortaise (13c.), possibly from Arabic murtazz "fastened," past participle of razza "cut a mortise in." Cf. Spanish mortaja.
mid-15c., from mortise (n.). Related: Mortised; mortising.