What is the meaning of fail?

verb

• Fail to do something; leave something undone.
  • usage: "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"
  • synonyms: neglect
• Be unsuccessful.
  • usage: "Where do today's public schools fail"; "The attempt to rescue the hostages failed miserably"
  • synonyms: go wrong, miscarry
• Disappoint, prove undependable to; abandon, forsake.
  • usage: "His sense of smell failed him this time"; "His strength finally failed him"; "His children failed him in the crisis"
  • synonyms: betray
• Stop operating or functioning.
  • usage: "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"
  • synonyms: go bad, give way, die, give out, conk out, go, break, break down
• Be unable.
  • usage: "I fail to understand your motives"
• Judge unacceptable.
  • usage: "The teacher failed six students"
• Fail to get a passing grade.
  • usage: "She studied hard but failed nevertheless"; "Did I fail the test"
  • synonyms: flunk, bomb, flush it
• Fall short in what is expected.
  • usage: "She failed in her obligations as a good daughter-in-law"; "We must not fail his obligation to the victims of the Holocaust"
• Become bankrupt or insolvent; fail financially and close.
  • usage: "The toy company went bankrupt after the competition hired cheap Mexican labor"; "A number of banks failed that year"
• Prove insufficient.
  • usage: "The water supply for the town failed after a long drought"
  • synonyms: run out, give out
• Get worse.
  • usage: "Her health is declining"