fortification

noun

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