fail (v.) Look up fail at Dictionary.com
early 13c., from Old French falir (11c., Modern French faillir) "be lacking, miss, not succeed," from Vulgar Latin *fallire, from Latin fallere "to trip, cause to fall;" figuratively "to deceive, trick, dupe, cheat, elude; fail, be lacking or defective." Related: Failed; failing. Replaced Old English abreoðan.
fail (n.) Look up fail at Dictionary.com
late 13c. (as in without fail), from Old French faile "deficiency," from falir (see fail (v.)). The Anglo-French form of the verb, failer, also came to be used as a noun, hence failure.