An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) To be unsuccessful in achieving something expected, attempted, or desired.
2) To neglect to do something.
3) To be e unsuccessful in an examination.

M.E. failen, from O.Fr. falir "be lacking, miss, not succeed; come to an end; make a mistake; be dying," from Vulgar L. *fallire, from L. fallere "to trip, cause to fall;" figuratively "to deceive, trick, dupe, cheat; fail, be lacking or defective."

Qâvidan, from Choresmian γaw "to fail, to commit a fault;" cf. Av. gau- "to commit a sin;" Parthian (+*fra-) pargaw- "to owe, to lack;" Ossetian qaewyn/qyd "to be in need of something, to lack;" Proto-Ir. *gaHu- "to be faulty, wanting; to need;" PIE *g^heHu- "to be faulty, lacking, insufficient;" cf. Old L. hauelod "insufficient, false," L. hau(d) "not;" O.Irish gáu, gó; Welsh gau "lie" (Cheung 2007).

1) An act or instance of failing; lack of success.
2) A state of inability to perform a normal function.

Verbal noun from → fail.