monoid
/ˈmɒnɔɪd/Mathematics
noun
1A surface which possesses a conical point of the highest possible order (i.e. n − 1, where n is the order of the equation defining the surface). Now rare.
2A semigroup possessing an identity element.
Origin
Mid 19th century (in an earlier sense). From mono- + -oid. With monoid surface, compare French surface monoïde.