fortress

Etymology

Early 14 c., from Old French forteresce, forteresse, forterece (“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, largesse and riches. For change of medial -l- to -r- in Old French, compare orne (“elm”) from ulmus; chartre from cartula and chapitre from capitulum. First attested in the from 12th century.

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.
   Like the Mesolithic age of 10,000-8000 B.C., the period 6000-4000 B.C. seems to be one of the fall of fortresses and the rise of pastoral nomadism. 1981, William Irwin Thompson, The Time Falling Bodies Take to Light: Mythology, Sexuality and the Origins of Culture, London: Rider/Hutchinson & Co., page 160
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.