sporadic group

Etymology
The earliest usage is thought to be that of English mathematician in 1911, W. Burnside, Theory of Groups of Finite Order, 2nd Edition, in a comment about the.

Noun

 * 1)  Any one of the 26 exceptional finite simple groups, which do not belong to any of the general, infinite categories specified by the.

Usage notes
The largest sporadic group is called the monster group (or Fischer–Griess monster group). All but six of the other groups are subquotients of the monster group; together with the latter, they form the Happy Family. The remaining six are called pariah groups.

Hyponyms

 * ,, , (= monster group), , , , , , , , , , , , ,