\For"tress\, n.; pl. {Fortresses}. [F. forteresse, OF.
forteresce, fortelesce, LL. foralitia, fr. L. fortis strong.
See {Fort}, and cf. {Fortalice}.]
A fortified place; a large and permanent fortification,
sometimes including a town; a fort; a castle; a stronghold; a
place of defense or security.
Syn: {Fortress}, {Fortification}, {Castle}, {Citadel}.
Usage: A fortress is constructed for military purposes only,
       and is permanently garrisoned; a fortification is
       built to defend harbors, cities, etc.; a castle is a
       fortress of early times which was ordinarily a
       palatial dwelling; a citadel is the stronghold of a
       fortress or city, etc.

\For"tress\, v. t.
To furnish with a fortress or with fortresses; to guard; to
fortify. --Shak.