fortification

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The science of fortifying.
2. n. The act or process of fortifying.
3. n. Something that serves to fortify, especially military works erected to fortify a position or place.

Century Dictionary and Cyclopedia

1. n. The act of fortifying or strengthening.
2. n. The art or science of strengthening military positions in such a way that they may be defended by a body of men much inferior in number to those by whom they are attacked.
3. n. That which fortifies, strengthens, or protects.
4. n. Specifically A military work, consisting of a wall, ditch, palisades, etc., constructed for the purpose of strengthening a position; a fortified place; a fort; a castle. Fortifications are divided into permanent and temporary or field fortifications. Permanent fortifications are works required to remain effective for any length of time, for the purpose of defending important positions, as cities, harbors, arsenals, etc. Temporary or field fortifications are designed to strengthen a post that is to be occupied only for a limited period. The figure represents it section of a fortified wall. a, a, is the abatis; b, b, the counterscarp; c, c, the palisade; d, d, the scarp; f, f, the fraise; fe, g, g, the parapet; h, the banquette; and i, g, the breast-height. For definitions of these, see the words.
5. n. the polygonal or caponiere system
6. n. the tenailled system, and
7. n. the bastioned system. To these in modern times may be added the armored or turreted system. Mahan. Synonyms Fortification, Bulwark, Castle, Citadel, Fort, Fortress, Mamelon, Rampart, Redan, Redoubt. Fortification is the only one of these words that is used for the art or science, or for all classes of defensive works; the others represent kinds of fortification. Thus, fortress represents a large, and fort, generally, but not always, a smaller stronghold, defensible on all sides, as Fortress Monroe, Fort Sumter. See the definitions of the words.

Wiktionary

1. n. The act of fortifying; the art or science of fortifying places to strengthen defence against an enemy.
2. n. That which fortifies; especially, a work or works erected to defend a place against attack; a fortified place; a fortress; a fort; a castle.

GNU Webster's 1913

1. n. The act of fortifying; the art or science of fortifying places in order to defend them against an enemy.
2. n. That which fortifies; especially, a work or works erected to defend a place against attack; a fortified place; a fortress; a fort; a castle.

WordNet 3.0

1. n. defensive structure consisting of walls or mounds built around a stronghold to strengthen it
2. n. the addition of an ingredient for the purpose of enrichment (as the addition of alcohol to wine or the addition of vitamins to food)
3. n. the art or science of strengthening defenses