Pronunciation: (on, ôn),[key] —prep. 1. so as to be or remain supported by or suspended from: Put your package down on the table; Hang your coat on the hook. 2. so as to be attached to or unified with: Hang the picture on the wall. Paste the label on the package. 3. so as to be a covering or wrapping for: Put the blanket on the baby. Put aluminum foil on the lamb chops before freezing them. 4. in connection, association, or cooperation with; as a part or element of: to serve on a jury. 5. so as to be a supporting part, base, backing, etc., of: a painting on canvas; mounted on cardboard; legs on a chair. 6. (used to indicate place, location, situation, etc.): a scar on the face; the book on the table; a house on 19th Street. 7. (used to indicate immediate proximity): a house on the lake; to border on absurdity. 8. in the direction of: on the left; to sail on a southerly course. 9. (used to indicate a means of conveyance or a means of supporting or supplying movement): on the wing; This car runs on electricity. Can you walk on your hands? I'll be there on the noon plane. 10. by the agency or means of: drunk on wine; talking on the phone; I saw it on television. 11. in addition to: millions on millions of stars. 12. with respect or regard to (used to indicate the object of an action directed against or toward): Let's play a joke on him. Write a critical essay on Shakespeare. 13. in a state or condition of; in the process of: on strike; The house is on fire! 14. subject to: a doctor on call. 15. engaged in or involved with: He's on the second chapter now. 16. (used to indicate a source or a person or thing that serves as a source or agent): a duty on imported goods; She depends on her friends for encouragement. 17. (used to indicate a basis or ground): on my word of honor; The movie is based on the book. 18. (used to indicate risk or liability): on pain of death. 19. (used to indicate progress toward or completion of an objective): We completed the project on budget. 20. assigned to or occupied with; operating: Who's on the switchboard this afternoon? 21. Informal.so as to disturb or affect adversely: My hair dryer broke on me. 22. Informal.paid for by, esp. as a treat or gift: Dinner is on me. 23. taking or using as a prescribed measure, cure, or the like: The doctor had her on a low-salt diet. 24. regularly taking or addicted to: He was on drugs for two years. 25. Informal.with; carried by: I have no money on me. 26. (used to indicate time or occasion): on Sunday; We demand cash on delivery. 27. (used to indicate the object or end of motion): to march on the capital. 28. (used to indicate the object or end of action, thought, desire, etc.): to gaze on a scene. 29. (used to indicate subject, reference, or respect): views on public matters. 30. (used to indicate an encounter): The pickpocket crept up on a victim. 31. on the bow,Naut.bow3 (def. 7).
—adv. 1. in, into, or onto a position of being supported or attached: Sew the buttons on. 2. in, into, or onto a position of covering or wrapping: Put your raincoat on. 3. fast to a thing, as for support: Hold on! 4. toward a place, point, activity, or object: to look on while others work. 5. forward, onward, or along, as in any course or process: further on. 6. with continuous activity: to work on. 7. into or in active operation or performance: Turn the gas on. 8. on and off, off (def. 22a).
9. on and on, at great length, so as to become tiresome: They rambled on and on about their grandchildren.
—adj. 1. operating or in use: The television set was on. Is your brake on? 2. taking place; occurring: Don't you know there's a war on? 3. performing or broadcasting: The radio announcer told us we were on. 4. Informal. a. behaving in a theatrical, lively, or ingratiating way: Around close friends, one doesn't have to be on every minute. b. functioning or performing at one's best: When she's on, no other tennis player is half as good. 5. scheduled or planned: Anything on after supper? 6. Baseball.positioned on a base or bases: They had two men on when he hit the home run. 7. Cricket.noting that side of the wicket, or of the field, on which the batsman stands.
8. on to, aware of the true nature, motive, or meaning of: I'm on to your little game.
—n. Cricket.the on side.
Pronunciation: (on),[key] —n. Biblical name of Heliopolis.
1. Old Norse. Also,ON.,O.N. 2. Ontario, Canada (approved for postal use).
a suffix used in the names of subatomic particles (gluon; meson; neutron), quanta (graviton), and other minimal entities or components (cistron; codon; magneton; photon).
a suffix used in the naming of inert gaseous elements: neon.