monad

Hence Leibnitz, who looked upon things as noumena, after denying them everything like external relation, and therefore also composition or combination, declared that all substances, even the component parts of matter, were simple substances with powers of representation, in one word, monads.

Coordinate term: comonad

The properties that make the Maybe type a monad are its type constructor Maybe a, our chaining function (>>?), and the injector function Just.