(Internet slang) Initialism of for some reason.

(US) Initialism of flexible spending account. / (Canada) Initialism of forward sortation area (postal system code) / (computer science) Initialism of finite-state automaton.

(UK) Initialism of Financial Services Authority. / (US) Initialism of Foreign Service Assignment.

(computing) A *nix file system check to detect damage to, or corruption of, files or filesystem structures.

(computing) The tool, fsck, that performs a fsck.

(computing, transitive) To run fsck on; to perform a fsck on.

(computing, Internet slang, text messaging, vulgar, euphemistic) Fuck.

(computing) Initialism of front-side bus.

(initialism, Russia, politics, espionage, government) The Federal Security Service of the Russian Federation (an intelligence agency of the Russian Federation and one of the main successors of the Soviet Cheka, NKVD, and KGB).

Initialism of follicle stimulating hormone.