Real Dictionary

failure
Your failure to do a particular thing is the fact that you do not do it, even though you were expected to do it.
countable noun: If something is a failure, it is not a success.
countable noun: If you say that someone is a failure, you mean that they have not succeeded in a particular activity, or that they are unsuccessful at everything they do.
uncountable noun: Failure is a lack of success in doing or achieving something, especially in relation to a particular activity.

failure in American English
the act of failing or the state or condition resulting from having failed
noun: an act or instance of failing or proving unsuccessful; lack of success

failure in British English
noun: the act or an instance of failing