“Singular thing” (res singulares) is one of the terms Spinoza uses to denote finite particulars. The term figures prominently in most of his philosophical works (with the exception of the TTP, where it figures only briefly in the account of prophecy, and the TP, where the term goes unused). However, its precise meaning evolves from its earliest appearance in the TIE to its final appearance in the Ethics. In the Ethics, the definition of the term (i) stipulates that singular things are finite and (ii) specifies the conditions under which many things compose one singular thing. However, in Spinoza’s earlier writings, the term is not restricted to finite and mutable things, nor is it associated with the composition of one (singular) thing from many distinct things. This short entry traces those shifts in meaning.