A data type composed of multiple elements.An aggregate can be homogeneous (all elements have the same type) e.g. an array, a list in a functional language, a string of characters, a fileor it can be heterogeneous (elements can have different types) e.g. a structure.In most languages aggregates can contain elements which are themselves aggregates. e.g. a list of lists.See also union.(1996-03-23)