c. 1600, "a name" (a sense now obsolete), from French nomenclature (16c.), from Latin nomenclatura "calling of names," from nomenclator "namer," from nomen "name" (from PIE root *no-men- "name") + calator "caller, crier," from calare "call out" (from PIE root *kele- (2) "to shout").
Nomenclator in Rome was the title of a steward whose job was to announce visitors, and also of a prompter who helped a stumping politician recall names and pet causes of his constituents. Meaning "systematic list or catalogue of names" is attested from 1630s; that of "system of naming" is from 1660s; sense of "whole vocabulary or terminology of an art or a science" is from 1789. Related: Nomenclative; nomenclatorial; nomenclatural.