Both definite descriptions and pronouns are often anaphoric; that is, part of their interpretation in context depends on prior linguistic material in the discourse. For example:
(1) A student walked in. The student sat down.
(2) A student walked in. She sat down.
One popular view of anaphoric pronouns, the d-type view, is that pronouns like “she” go proxy for definite descriptions like “the student who walked in”, which are in turn treated in a classical (neo-) Russellian or (neo-) Fregean fashion. I argue for a novel version of the d-type view in which anaphoric definites are restricted existential quantifiers that presuppose discourse uniqueness, which is uniqueness of discourse referent in the context, rather than uniqueness of object in the world. In other words, the anaphoric definites “the student” and “she” in (1) and (2) presuppose that there is a single object under discussion that is a student who walked in. I further argue that, by contrast, non-anaphoric definites are restricted existential quantifiers that presuppose worldly uniqueness, that is, that there is a unique object in the world that satisfies the descriptive information. The semantics for anaphoric and non-anaphoric definites accounts for the differences in truth conditions in discourses involving the two different types of definites, improving on existing accounts. It is further supported by cross-linguistic data.