noun Nautical. 1.the third mast from forward in a vessel having three or more masts. See illus. under
quarterdeck.
2.the after and shorter mast of a yawl, ketch, or dandy; jiggermast.
Also, miz·en·mast.
Origin: 1375–1425; late Middle English meson mast. See
mizzen,
mast1