Definition of "fortress" in English

noun

1. 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.

2. (chess) A position that, if obtained by the weaker side, will prevent penetration by the opposing side, generally achieving a draw.

verb

1. (transitive) To furnish with a fortress or with fortresses; to guard, to fortify.