Definitions:

1. in a state required for something to function or be effective adverb
   • turn the lights on
2. in operation or operational adjective
   • left the oven on
3. indicates continuity or persistence or concentration adverb
   • The band's spirit lives on in the music they made.
4. of events, planned or scheduled adjective
   • The picnic is on, rain or shine.
5. with a forward motion adverb
   • we drove along admiring the view

Synonyms:

• along