genus Mastotermes ge·nus·mas·totermes uncommon noun 1. primitive genus of termites; mostly extinct; sometimes considered the most primitive Isoptera SynonymsMastotermesgenus Mastotermes Related words Broader terms arthropod genus Parts Mastotermitidae Part of Mastotermes darwiniensisMastotermes electromexicusMastotermes electrodominicus WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.