on

Etymology 1

From Middle English on, from Old English on, an (“on, upon, onto, in, into”), from Proto-West Germanic *ana, from Proto-Germanic *ana (“on, at”), from Proto-Indo-European *h₂en-. Cognate with North Frisian a (“on, in”), Saterland Frisian an (“on, at”), West Frisian oan (“on, at”), Dutch aan (“on, at, to”), Low German an (“on, at”), German an (“to, at, on”), Swedish å (“on, at, in”), Faroese á (“on, onto, in, at”), Icelandic á (“on, in”), Gothic 𐌰𐌽𐌰 (ana), Ancient Greek ἀνά (aná, “up, upon”), Albanian në (“in”); and from Old Norse upp á: Danish på, Swedish på, Norwegian på, see upon.

adj

1. In the state of being active, functioning or operating.
   All the lights are on, so they must be home.
2. Performing according to schedule; taking place.
   Are we still on for tonight?
   Is the show still on?
   We had to ration our food because there was a war on.
   That TV programme that you wanted to watch is on now.
3. Fitted; covering; being worn.
   Your feet will soon warm up once your socks are on.
   I was trying to drink out of the bottle while the top was still on!
4. (postpositive) Of a stated part of something, oriented towards the viewer or other specified direction.
   The photograph shows the UFO side on.
   edge on, side on, end on, face on
5. (chiefly UK, informal, usually negative) Acceptable, appropriate.
   You can't do that; it's just not on.
   This kind of over-packaging of goods is completely not on. May 22 1998, Phoenix Gamma, “If I was owned Nintendo...”, in alt.games.video.nintendo-64 (Usenet)
   so Simon Nelson saying on Feedback "we'd prefer it if everybody listened to digital radio via DAB" is completely not on at all. August 12 2003, DAB sounds worse than FM, “Gerg Dyke's Speech at Radio Festival”, in alt.radio.digital (Usenet)
6. (informal) Destined, normally in the context of a challenge being accepted; involved, doomed.
   "Five bucks says the Cavs win tonight." ―"You're on!"
   Mike just threw coffee onto Paul's lap. It's on now.
7. (baseball, informal) Having reached a base as a runner and being positioned there, awaiting further action from a subsequent batter.
   With one out and no men on, Tristen Carranza belted a ball to the opposite field for a solo home run to put the NM State deficit at just 2-1. 2019-02-24, Chris Kennedy, “Aggies Earn Series Win Over Yale in Sunday Finale”, in New Mexico State University Athletics
   Although Stanford was outhit 15-6, the Cardinal stranded eight runners to UCLA's three, hitting just 3-15 with runners on compared to the Bruin's 9-22. 2019-04-06, Daniel Martinez-Krams, “Baseball Falls Short in Game 2 of UCLA Series”, in The Stanford Daily
8. (cricket) Within the half of the field on the same side as the batsman's legs; the left side for a right-handed batsman.
   ;
   The captain moved two fielders to the on side.
   Ponsonby-Smythe hit a thumping on drive.
9. (acting, drama, roleplaying games) Acting in character.
10. (euphemistic) Menstruating.
    It still gets in the way of her doing things like swimming, and she avoids sleepovers when she's "on". 2011, Hollie Smith Netmums, You and Your Tween: Managing the years from 9 to 13, Hachette
11. (informal, of a person) Performative or funny in a wearying manner.
    He always has to be on, it's so exhausting.

adv

1. To an operating state.
   turn the television on
2. So as to cover or be fitted.
   The lid wasn't screwed on properly.
   Put on your hat and gloves.
3. Along, forwards (continuing an action).
   drive on, rock on
   He met Luis Suarez's cross at the far post, only for Chelsea keeper Petr Cech to show brilliant reflexes to deflect his header on to the bar. Carroll turned away to lead Liverpool's insistent protests that the ball had crossed the line but referee Phil Dowd and assistant referee Andrew Garratt waved play on, with even a succession of replays proving inconclusive. May 5, 2012, Phil McNulty, “Chelsea 2-1 Liverpool”, in BBC Sport
4. In continuation, at length.
   and so on
   He rambled on and on.
5. (obsolete in the US) Later.
   Ten years on, nothing had changed in the village.
6. Of betting odds, denoting a better-than-even chance. See also odds-on.
   That horse is twenty-to-one on, so you need to stake twenty pounds just to win one pound.

prep

1. Positioned at the upper surface of, touching from above.
   A vase of flowers stood on the table.
   Please lie down on the couch.
   The parrot was sitting on Jim's shoulder.
   I stood on the bridge at midnight. 1845, Henry Wadsworth Longfellow, The Bridge
2. Positioned at or resting against the outer surface of; attached to.
   He had a scar on the side of his face.
   There is a dirty smudge on this window.
   The painting hangs on the wall.
   The fruit ripened on the trees.
3. Expressing figurative placement, burden, or attachment.
   All of the responsibility is on him.
   I put a bet on the winning horse.
4. Denoting performance or action by contact with the surface, upper part, or outside of anything; hence, by means of; with.
   to play on a violin or piano
5. At or in (a certain region or location).
   The lighthouse that you can see is on the mainland.
   The suspect is thought to still be on the campus.
6. Near; adjacent to; alongside; just off.
   The fleet is on the American coast.
   Croton-on-Hudson, Rostov-on-Don, Southend-on-Sea
7. Supported by (the specified part of itself).
   A table can't stand on two legs.
   After resting on his elbows, he stood on his toes, then walked on his heels.
8. So as to impart force to.
   tug on the rope; push hard on the door
9. So as to impact; against.
   I stubbed my toe on an old tree stump.
10. Covering.
    He wore old shoes on his feet.
11. (with certain modes of transport, especially public transport) Inside (a vehicle) for the purpose of travelling.
    on a bus, on a train, on a plane
12. At the date of.
    Born on the 4th of July.
13. Sometime during the day of.
    On Sunday I'm busy. I'll see you on Monday.
    Can I see you on a different day?
14. At a given time after the start of something; at.
    Smith scored again on twelve minutes, doubling Mudchester Rovers' lead.
    I'll see you a week on Friday.
    The Spain striker had given Chelsea the lead on 29 minutes but was shown a straight red card 10 minutes later for a rash challenge on Mark Gower. September 24, 2011, Aled Williams, “Chelsea 4-1 Swansea”, in BBC Sport
15. Dealing with the subject of; about; concerning.
    I was reading a book on history.
    The city hosted the World Summit on the Information Society
    I have no opinion on this subject.
16. (informal) In the possession of.
    I haven't got any money on me.
17. Because of; due to; upon the basis of (something not yet confirmed as true).
    to arrest someone on suspicion of bribery
    to contact someone on a hunch
18. Upon; at the time of (and often because of).
    On Jack's entry, William got up to leave.
    On the addition of ammonia, a chemical reaction begins.
19. Paid for by.
    The drinks are on me tonight, boys.
    The meal is on the house.
    I paid for the airfare and meals for my family, but the hotel room was on the company.
20. Indicating a means or medium.
    I saw it on television.
    Can't you see I'm on the phone?
    My favorite shows are on BBC America.
    The Beatles' appearance on the Ed Sullivan Show is on YouTube.
    The film was released on DVD.
21. Indicating the target of, or thing affected by, an event or action.
    They planned an attack on London.
    The soldiers mutinied and turned their guns on their officers.
    Her words made a lasting impression on my mind.
    What will be the effect on morale?
22. Toward; for; indicating the object of an emotion.
    Have pity or compassion on him.
23. (especially Ireland) Indicating the person experiencing an emotion, cold, thirst, hunger, etc.
    '[…] the hunger is on me to carry my sword in distant places.' Mynyddog bowed his head. 2013-02-27, Rosemary Sutcliff, The Shining Company, Random House
    “Christ, the thirst on me.” “Sure, it's serious work, all that talk of independence.” The theater's stained-glass doors had first flung open in 1904, all in the hope of “rewriting the Irish identity,” of using culture in the fight[…] 2017-01-24, Ruth Gilligan, Nine Folds Make a Paper Swan, Tin House Books
    “I've got the hunger on me, I do.” Riordan snorted. Hardly a man knew hunger as he did. The prison rations at Point Lookout, spare enough, had been a feast compared to the black years in Ireland.[…] 2017-08-29, Ralph Peters, Judgment at Appomattox: A Novel, Forge Books, page 18
24. Indicating a means of subsistence.
    They lived on ten dollars a week.
    The dog survived three weeks on rainwater.
25. Engaged in or occupied with (an action or activity).
    He's on his lunch break.
    I'm on nights all this week.
    on vacation; on holiday; on the job; on the fiddle
26. Regularly taking (a drug).
    You've been on these antidepressants far too long.
    He's acting so strangely, I think he must be on something.
27. Under the influence of (a drug, or something that is causing drug-like effects).
    He's acting crazy because he's on crack right now.
28. (mathematics) Having identical domain and codomain.
    a function on
29. (mathematics) Having Vⁿ as domain and V as codomain, for some set V and integer n.
    an operator on
30. (mathematics) Generated by.
    the free group on four letters
31. In addition to; besides; indicating multiplication or succession in a series.
    heaps on heaps of food
    mischief on mischief; loss on loss
32. (obsolete, regional) of
33. Indicating dependence or reliance.
    I depended on them for assistance.
    He will promise on certain conditions.
34. (obsolete) At the peril of, or for the safety of.
35. Serving as a member of.
    He is on the jury; I am on the committee.
36. By virtue of; with the pledge of.
    He affirmed or promised on his word, or on his honour.
37. To the account or detriment of; denoting imprecation or invocation, or coming to, falling, or resting upon.
    On us be all the blame.
    A curse on him!
    Please don't tell on her and get her in trouble.
    He turned on her and has been her enemy ever since.
    He went all honest on me, making me listen to his confession.
38. (especially when numbers of combatants or competitors are specified) Against; in opposition to.
    The fight was three on one, and he never stood a chance.
39. (philosophy, logic) According to, from the standpoint of; expressing what must follow, whether accepted or not, if a given premise or system is assumed true.
    On naturalism, it is therefore difficult to find a ground for ultimate moral hope. 2021, Gavin Ortlund, Why God Makes Sense in a World That Doesn't: The Beauty of Christian Theism, Grand Rapids, MI: Baker Academic

verb

1. (Singapore, Philippines, Malaysia, Nigeria, transitive, colloquial) To switch on.
   Can you on the light?

Etymology 2

From Old Norse ón, án (“without”), from Proto-Germanic *ēnu, *ēno, *ino (“without”), from Proto-Indo-European *ḗnu (“without”). Cognate with North Frisian on (“without”), Middle Dutch an, on (“without”), Middle Low German āne (“without”), German ohne (“without”), Gothic 𐌹𐌽𐌿 (inu, “without, except”), Ancient Greek ἄνευ (áneu, “without”).

prep

1. (UK dialectal, Scotland) Without.

Etymology 3

From Japanese 音読み (on'yomi, literally “sound reading”).

noun

1. In the Japanese language, a pronunciation, or reading, of a kanji character that was originally based on the character's pronunciation in Chinese, contrasted with kun.
   Most kanji have two kinds of reading, called "on" and "kun".