mid-15c., "fortified place, stronghold," from Old French fort "fort, fortress; strong man," noun use of adjective meaning "strong, stout, sturdy; hard, severe, difficult; hard to understand; dreadful, terrible; fortified" (10c.), from Latin fortis "strong, mighty; firm, steadfast; brave, spirited," from Old Latin forctus, which is of unknown etymology. Possibly from PIE root *bhergh- (2) "high, elevated," with derivatives referring to hills and hill-forts, or possibly from *dher- "to hold firmly, support." Figurative use of hold the fort attested from 1590s.

1640s, fort, from French fort "strong point (of a sword blade)," earlier "fort, fortress" (see fort). Meaning "strong point of a person, that in which one excels," is from 1680s. Final -e- added 18c. in imitation of Italian forte "strong."

Estonian capital, from Old Estonian (Finnic) tan-linn "Danish fort," from tan "Danish" + linn "fort, castle." Founded 1219 by Danish king Valdemar II.

county in northern Ireland, from Irish Dun na nGall "fort of the foreigners" (in this case, the Danes); also see Galloway.

1724, from Italian fortissimo, superlative of forte "loud, strong," from Latin fortis "strong" (see fort).

music instruction, "loud, loudly," from Italian forte, literally "strong," from Latin fortis "strong" (see fort). Opposed to piano.

1520s, "mystical interpretation of the Old Testament," later "an intriguing society, a small group meeting privately" (1660s), from French cabal, which had both senses, from Medieval Latin cabbala (see cabbala). Popularized in English 1673 as an acronym for five intriguing ministers of Charles II (Clifford, Arlington, Buckingham, Ashley, and Lauderdale), which gave the word its sinister connotations.

1931 as a term in psychics and later (1951) science fiction; from tele- + (trans)portation. Apparently coined by Charles Fort (1874-1932).

"detached fort blocking a landing, mountain pass, etc., 1510s, of uncertain origin; perhaps from Middle Dutch blokhuis, German Blockhaus, French blockhaus (which is from one of the German words), all from 16c.; see block (v.1). Later "building with an overhanging upper story with loopholes for firing through" (often a square of logs serving as a fort in rough country), which seems to connect it to block (n.1). For second element, see house (n.).

port city in southwestern Spain, from Latin Gades (Greek Gadeira), from Phoenician gadir "fort, enclosure." Related: Gaditan (from Latin adjective Gaditanus).