Flunk

verb

1. To lose strength weaken

   "her health was failing"

2. To fade or die away

   "until our family line fails"

3. To stop functioning normally

   "the patient's heart failed"

4. To fall short

   "failed in his duty"

5. To be or become absent or inadequate

   "the water supply failed"

6. To be unsuccessful

   "the marriage failed"

7. To become bankrupt or insolvent

   "banks were failing"

8. To disappoint the expectations or trust of

   "her friends failed her"

9. To miss performing an expected service or function for

   "his wit failed him"

10. To be deficient in lack

    "never failed an invincible courage"

11. To leave undone neglect

    "fail to lock the door"

12. To be unsuccessful in passing

    "failed chemistry"

13. To grade (someone, such as a student) as not passing

    "The teacher failed only his two worst students."

noun

1. Failure
2. A failure (as by a security dealer) to deliver or receive securities within a prescribed period after purchase or sale
3. failure —usually used in the phrase without fail
4. a failure (as by a security dealer) to deliver or receive securities within a prescribed period after purchase or sale

adjective

1. Incorporating some feature for automatically counteracting the effect of an anticipated possible source of failure
2. Being or relating to a safeguard that prevents continuing on a bombing mission according to a preconceived plan
3. Having no chance of failure infallibly problem-free

   "the little black dress … has consistently been the fail-safe solution for night"

noun

1. A device or measure that makes something fail-safe

idiom

1. To not understand

noun

1. A notable, obvious, and usually public failure

   "What was supposed to be a kind gesture turned into an epic fail, and now a viral video. … Morgan accidentally missed the step and faceplanted into the front door."

adjective

1. Being a system of grading whereby the grades "pass" and "fail" replace the traditional letter grades

idiom

1. Used to stress that something always happens
2. Used to stress that something will definitely happen

idiom

1. Used to say that a person does not know what to say