A set endowed with an everywhere defined binary relation on it. No conditions are imposed. In particular, a magma need not be commutative or associative. Of particular importance is the free magma on an alphabet (set) . A mapping of one magma into another is a morphism of magmas if for all , i.e., if it respects the binary relations.
Magma. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Magma&oldid=34696