1. adjective /ɒn,ɑn,ɔn/
Are we still on for tonight?
b) performing according to schedule
Is the show still on?
2. adverb /ɒn,ɑn,ɔn/
a) to an operating state
turn the television on
b) along, forwards (continuing an action)
drive on, rock on
3. preposition /ɒn,ɑn,ɔn/
on the table; on the couch
b) covering
Born on the 4th of July.
Wikipedia foundation.