1640s, from French fort "strong point (of a sword blade)," also "fort," from Middle French fort (see fort). Meaning "strong point of a person" is from 1680s. Final -e- added 18c. in imitation of Italian forte "strong."
music instruction, "loud, loudly," from Italian forte, literally "strong," from Latin fortis "strong" (see fort).
A musical direction meaning “to be performed loudly”; the opposite of piano.
Note: The common keyboard instrument the pianoforte (“piano” for short) got its name because it could play both soft and loud notes.