Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
nōmenclātūra, ae, f. [nomen-calo], a calling by name, a list of names, nomenclature (Plinian), Plin. H. N. 3 prooem. § 2; id. 21, 9, 28, § 52.