Definition of mate noun in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more. The meaning of MATE is checkmate. How to use mate in a sentence. Yerba mate or yerba maté (/ ˈjɜːrbə ˈmɑːteɪ /), [2][3] Ilex paraguariensis, is a plant species of the holly genus native to South America. [4] It was named by the French botanist Augustin Saint-Hilaire. [5] The leaves of the plant can be steeped in hot water to make a beverage known as mate . Brewed cold, it is used to make tereré. Both the plant and the beverage contain caffeine. The indigenous Guaraní and some Tupi communities (whose territory covered present-day Paraguay) first ... 13 meanings: 1. the sexual partner of an animal 2. a marriage partner 3. a. informal, mainly British, Australian and New.... Click for more definitions.