1) Preposition; Above and touching a surface.
2) Adverb; Working, conducting their intended task.
3) Prefix; Continuously, continuing.
4)
Slang Verb; To be menstruating.
1) I was on
your mother all
night.
2) Your computer is currently on.
3) The project is ongoing.
4)
WOMAN: "I'm on at the minute. Fucking men, they're all bastards..."