NOUN (1)

1. a commodity that is freely interchangeable with another in satisfying an obligation;


ADJECTIVE (1)

1. of goods or commodities; freely exchangeable for or replaceable by another of like nature or kind in the satisfaction of an obligation;

WordNet (r) 3.0 (2006):

fungible
    adj 1: of goods or commodities; freely exchangeable for or
           replaceable by another of like nature or kind in the
           satisfaction of an obligation
    n 1: a commodity that is freely interchangeable with another in
         satisfying an obligation