Other forms: fortresses
A fortress is a large strongly defended building. An ancient fortress, the fortress fell, a fortress town.
It differs from a castle in purpose rather than size: a castle is a lord's residence that is also defended, where a fortress exists to be defended and nothing else. Artillery ended the tall wall and forced the low angled one. Note the Latin fortis, strong.
1nounfortressA large strongly defended building.
“The soldiers defended the fortress on the hill for months.”
fortress is a defended building.
Old French forteresce comes from Latin fortis, strong. Fort and force come from the same strength.
Latin
fortis — strong
Medieval Latin
fortalitia
Old French
forteresce — strong place, fortification
English, today
fortress
Built from
Early 14 c., from Old French forteresce (“strong place, fortification”), variant of fortelesse, from Medieval Latin fortalitia, from Latin fortis (“strong”) (see fort)itia, added to adjectives to form nouns of quality or condition. French -ess, from Latin -itia is also in words such as duress, prowess, largesse and richesse. For change of medial -l- to -r- in Old French, compare orne (“elm”) from ulmus; chartre from cartula and chapitre from capitulum. 12th century.
Etymology from Wiktionary, CC BY-SA