(geography) A hard surface of rock fragments set in a sandy matrix, found in some hot deserts; regolith, stony desert.

(mathematics) A theorem stating that, if L is a complete lattice and f : L → L is an order-preserving function, then the set of fixed points of f in L is also a complete lattice. It has important a...

A retiree, especially one who has retired later than the normal retirement age

A playing piece in the game of checkers (British: draughts). / A pattern of alternating colours as on a chessboard. / An individual square appearing in such a pattern.