1. to fall short of success or achievement in something expected, attempted, desired, or approved: The experiment failed because of poor planning.
2. to receive less than the passing grade or mark in an examination, class, or course of study: He failed in history.
3. to be or become deficient or lacking; be insufficient or absent; fall short: Our supplies failed.
4. to dwindle, pass, or die away: The flowers failed for lack of rain.
5. to lose strength or vigor; become weak: His health failed after the operation.
6. to become unable to meet or pay debts or business obligations; become insolvent or bankrupt.
7. (of a building member, structure, machine part, etc.) to break, bend, crush, or be otherwise destroyed or made useless because of an excessive load.
8. to stop functioning or operating: The electricity failed during the storm.
–verb (used with object)
9. to be unsuccessful in the performance or completion of: He failed to do his duty.
10. (of some expected or usual resource) to prove of no use or help to: His friends failed him. Words failed her.
11. to receive less than a passing grade or mark in: He failed history.
12. to declare (a person) unsuccessful in a test, course of study, etc.; give less than a passing grade to: The professor failed him in history.
13. Stock Exchange.
a. a stockbroker's inability to deliver or receive security within the required time after sale or purchase.
b. such an undelivered security.
14. Obsolete. failure as to performance, occurrence, etc.
15. without fail, with certainty; positively: I will visit you tomorrow without fail.
[Origin: 1175–1225; ME failen < AF, OF faillir < VL *fallīre, for L fallere to disappoint, deceive]