A property of a pair of binary operations. We say that the operation @ distributes on the left over the operation $ if (x@y)$z = (x$z) @ (y$z), and that it distributes on the right if x$(y@z) = (x$y)@(x$z) (if $ is commutative, each type implies the other, and we simply say the @ distributes over $).

For example, addition distributes over multiplication, but multiplication doesn't distribute over addition.