fail

n. failure to perform, failure to occur (Archaic)

v. be unsuccessful; make unsuccessful; not do; be weakened; disappoint; go bankrupt; be stopped; be used up, run out

In general, failure refers to the state or condition of not meeting a desirable or intended objective. It may be viewed as the opposite of success.
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Verb
1. fail to do something; leave something undone; "She failed to notice that her child was no longer in his crib"; "The secretary failed to call the customer and the company lost the account"
(synonym) neglect
(hyponym) strike out
(derivation) failure
2. be unsuccessful; "Where do today's public schools fail?"; "The attempt to rescue the hostages failed miserably"
(synonym) go wrong, miscarry
(antonym) succeed, win, come through, bring home the bacon, deliver the goods
(hyponym) take it on the chin
(derivation) failure
3. disappoint, prove undependable to; abandon, forsake; "His sense of smell failed him this time"; "His strength finally failed him"; "His children failed him in the crisis"
(synonym) betray
(hypernym) disappoint, let down
4. stop operating or functioning; "The engine finally went"; "The car died on the road"; "The bus we travelled in broke down on the way to town"; "The coffee maker broke"; "The engine failed on the way to town"; "her eyesight went after the accident"
(synonym) go bad, give way, die, give out, conk out, go, break, break down
(hypernym) change
(hyponym) crash, go down
(verb-group) die, decease, perish, go, exit, pass away, expire, pass
(derivation) failure
5. be unable; "I fail to understand your motives"
(antonym) pull off, negociate, bring off, carry off, manage
6. judge unacceptable; "The teacher failed six students"
(antonym) pass
(hypernym) judge
(verb-group) flunk, bomb, flush it
(derivation) failing
7. fail to get a passing grade; "She studied hard but failed nevertheless"; "Did I fail the test?"
(synonym) flunk, bomb, flush it
(antonym) pass, make it
(derivation) failing
8. fall short in what is expected; "She failed in her obligations as a good daughter-in-law"; "We must not fail his obligation to the victims of the Holocaust"
(verb-group) flunk, bomb, flush it
(derivation) failure
9. become bankrupt or insolvent; fail financially and close; "The toy company went bankrupt after the competition hired cheap Mexican labor"; "A number of banks failed that year"
(derivation) bankruptcy, failure
10. prove insufficient; "The water supply for the town failed after a long drought"
(synonym) run out, give out
11. get worse; "Her health is declining"
(hypernym) worsen, decline

n. doer, maker, subject, perpetrator, principal

See failure, graceful degradation.