v.tr. (-ies, -ied) 1 provide or equip with defensive works so as to strengthen against attack. 2 strengthen or invigorate mentally or morally; encourage. 3 strengthen the structure of. 4 strengthen (wine) with alcohol. 5 increase the nutritive value of (food, esp. with vitamins). fortifiable adj. fortifier n.
[ ME f. OF fortifier f. LL fortificare f. L fortis strong ]