A person who fails does not get what he or she tried to get. An opportunity is lost, or there is no achievement. The word "fail" is the opposite of the word "succeed."
These sentences show how to use "fail" as a verb:
An "F" stands for a failing grade.
Tom failed his math test. (past tense)
Tina failed to get the job that she wanted.
Terry won’t fail in school if he studies. (future tense, negative)
Todd fails to get to work on time. (present tense)
The two groups failed to come to an agreement.
The movie we saw failed to live up to the expectation we had for it.
That restaurant has failed to live up to its reputation for good food.
The power failed during the storm. (There was a power failure.)
Their business failed after six months.
My mouse is failing. I have to buy a new one. (The mouse for my computer isn’t working properly.)
The word "failure" is a noun. It can be used to refer to a person or a thing:
Small business failure in the United States is very common.
Bob and Marta’s marriage ended in failure.
Bertha never recovered from her failure in college.
The project ended in failure.
We had a power failure last night. (power failure = no electricity)
Failure can sometimes provide important lessons for future success.
Note: Very recently, the word "fail" has popularly been used as a one-word response or comment on anything that goes wrong or doesn’t meet general expectations. You’ll see the word "fail" pop up in tweets, on message boards, on Facebook, and other electronic media. The use of "fail" in this manner is unusual, so there’s a good chance that this is a fad and will not last.