the act of fortifying or strengthening.

something that fortifies or protects.

the art or science of constructing defensive military works.

Often, fortifications. military works constructed for the purpose of strengthening a position; a fort

Supposedly impregnable, the fortifications were quickly overrun.

a strengthening or improvement, as by addition of or intensification with another ingredient

the fortification of milk with vitamin D; the fortification of wine with alcohol.

noun

barricade , barrier , bastion , battlement , block , blockhouse , breastwork , buffer , bulwark , castle , citadel , consolidation , defense , earthwork , embattlement , entrenchment , fastness , fort , fortress , garrison , keep , outpost , parapet , preparation , presidio , protection , reinforcement , stockade , strengthening , stronghold , support , wall , moat , palisade , rampart , redan , retrenchment , shield , tower