¦ preposition
1. physically in contact with and supported by (a surface).
located somewhere in the general surface area of (a place).
on to.
in the possession of.
2. forming a distinctive or marked part of the surface of.
3. about; concerning.
having (something) as a basis.
4. as a member of (a committee, jury, etc.).
5. having (something) as a target, aim, or focus.
6. having (something) as a medium for transmitting or storing information.
being broadcast by (a radio or television channel).
7. in the course of (a journey).
while travelling in (a public service vehicle).
8. indicating the day or part of a day during which an event takes place.
at the time of.
9. engaged in.
10. regularly taking (a drug or medicine).
11. paid for by.
12. added to.
¦ adverb
1. physically in contact with and supported by a surface.
(of clothing) being worn by a person.
2. indicating continuation of a movement or action.
further forward; in an advanced state.
3. (of an event) taking place or being presented.
due to take place as planned.
4. (of an electrical appliance or power supply) functioning.
5. (of an actor) on stage.
(of an employee) on duty.
¦ noun (also on side) Cricket the leg side.
Phrases
be on about Brit. informal talk about tediously and at length.
be on at Brit. informal nag or grumble at.
be on to informal
1. be close to uncovering an illegal or undesirable activity engaged in by (someone).
2. (be on to something) have an idea that is likely to lead to an important discovery.
on and on continually; at tedious length.
on to moving to a location on the surface of (something) or aboard (a public service vehicle).
Origin
OE on, an, of Gmc origin.