The meaning of FORTIFY is to make strong. How to use fortify in a sentence. Did you know? FORTIFIED definition : 1. made stronger against attack, for example with high, strong walls: 2. (of a food) with vitamins…. Learn more. 6 meanings: 1. to make (a place) defensible, as by building walls, digging trenches, etc 2. to strengthen physically, mentally,.... Click for more definitions. Definition of fortified in the Definitions.net dictionary. Meaning of fortified . What does fortified mean ? Information and translations of fortified in the most comprehensive dictionary definitions resource on the web.