Fortification \For`ti*fi*ca"tion\, n. [L. fortificatio : cf. F. fortification.] 1. The act of fortifying; the art or science of fortifying places in order to defend them against an enemy. 2. That which fortifies; especially, a work or works erected to defend a place against attack; a fortified place; a fortress; a fort; a castle. {Fortification agate}, Scotch pebble. Syn: Fortress; citadel; bulwark. See {Fortress}.