Origin: Germanic Old English prefix
Fortress has 3 different meanings across 1 category:
A fortified place; a large and permanent fortification, sometimes including a town; for example a fort, a castle; a stronghold; a place of defense or security.
"The ancient fortress stood as an impenetrable stronghold on the hilltop, protecting the small town below from invaders."
In plain English: A fortress is an extremely strong building designed to protect people and things from enemies.
"The old castle looked like an impenetrable fortress standing on top of the hill."
Usage: Use "fortress" as a noun to describe a heavily fortified building or metaphorically to refer to something that is extremely secure or difficult to penetrate. Avoid using it as a verb in modern English, as this usage is now archaic and rarely understood outside of historical texts.
To furnish with a fortress or with fortresses; to guard, to fortify.
"The king ordered his engineers to fortress the vulnerable border towns against potential invasion."
In plain English: To fortress means to make something very strong and hard for anyone else to get into.
"The team will fortress their home game with extra security measures to ensure safety for all fans."
The word fortress entered English in the early 14th century via Middle French as a term for "strong place" or fortification. It ultimately derives from Latin fortis, meaning strong, combined with a suffix used to form nouns describing qualities.