failyoudaoicibaDictYouDict[fail 词源字典]
fail: [13] Fail, fallacy [15], fallible, false, and fault all come ultimately from the same source – the Latin verb fallere. This originally meant ‘deceive’, but it developed semantically to ‘deceive someone’s hopes, disappoint someone’, and in its Vulgar Latin descendant *fallīre this meaning had progressed to ‘be defective, fail’. English acquired the word via Old French faillir. Its Anglo-Norman form, failer, came to be used as a noun, and is the source of English failure [17].
=> faliacy, fallible, false, fault[fail etymology, fail origin, 英语词源]
fail (v.)youdaoicibaDictYouDict
c. 1200, "be unsuccessful in accomplishing a purpose;" also "cease to exist or to function, come to an end;" early 13c. as "fail in expectation or performance," from Old French falir "be lacking, miss, not succeed; run out, come to an end; err, make a mistake; be dying; let down, disappoint" (11c., Modern French faillir), 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. From c. 1200 as "be unsuccessful in accomplishing a purpose;" also "cease to exist or to function, come to an end;" early 13c. as "fail in expectation or performance." From mid-13c. of food, goods, etc., "to run short in supply, be used up;" from c. 1300 of crops, seeds, land. From c. 1300 of strength, spirits, courage, etc., "suffer loss of vigor; grow feeble;" from mid-14c. of persons. From late 14c. of material objects, "break down, go to pieces."
fail (n.)youdaoicibaDictYouDict
late 13c., "failure, deficiency" (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.