Entry 1 sense Webster, 1913 Fortifier /fôr'-təf-īˌ-ẽr/ · For·ti·fi·er · IPA /fˈɔrtəfˌaɪər/ 01 n. One who, or that which, fortifies, strengthens, supports, or upholds. 1. One who, or that which, fortifies, strengthens, supports, or upholds.