indefinite

a semantic feature characterizing entities whose extension is made indeterminate by the use of the article an (or nothing) and typically not identifiable to either speaker or hearer, ¶2-3-4, figure 6, ¶2-4-6, figure 13, ¶14-4-2, ¶14-4-3; i. is opposed to prototypical, indiscriminate, and quantitive