Cases of word usage

1) to fail to perform a duty, to appear (e.g. in a law court) or to a debt (default)

2) to fail to do or be equal to what is hoped for by (a person) (disappoint)

3) to fail (an examination) (flunk)

4) to fail to keep (something) in the memory (forget)

5) to fail to use the sounds /s/ and /z/ correctly (e.g. in sixteen) (lisp)

6) (of plans etc) to fail; (of letters etc) to fail to reach the destination (miscarry)

7) (of a gun) to fail to send a bullet (misfire)

8) to fail to have the correct idea or meaning about (a person, something said, written etc); to fail to identify the true character of (a person) (misunderstand)

9) to fail to include (a person, thing); decide and leave out (a person, thing) (omit)

10) fail to do; forget (overleap)