Synonyms for Determiner (same or very similar meaning)
WordNet sense 1 (an argument that is conclusive):
clincher, determining factorWordNet sense 2 (one of a limited class of noun modifiers that determine the referents of noun phrases):
determinativeWordNet sense 3 (a determining or causal element or factor):
determinant, causal factorFrom the ODE community, based on WordNetadd/edit