1. <mathematics, logic> Any mathematical expression in which an addition operator is applied to two or more subexpressions each of which is an application of a multiplication operator. The most common case would be scalar addition and multiplication, e.g.
ab + cdbut the term is used for other kinds of operators with similar properties, such as AND and OR in Boolean algebra, e.g.
(a AND b) OR (c AND d)2. <types> algebraic data type.