Dictionary.com
definitions

on

[on, awn]
See more synonyms for on on Thesaurus.com
preposition
  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, especially 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.
adverb
  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.
adjective
  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.
    1. behaving in a theatrical, lively, or ingratiating way: Around close friends, one doesn't have to be on every minute.
    2. 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.
noun
  1. Cricket. the on side.
Idioms
  1. on and off, off(def 54a).
  2. on and on, at great length, so as to become tiresome: They rambled on and on about their grandchildren.
  3. on the bow, Nautical. bow3(def 8).
  4. on to, aware of the true nature, motive, or meaning of: I'm on to your little game.

Origin of on

before 900; Middle English on, an, Old English: on, in, to; cognate with Dutch aan, German an, Old Norse ā, Gothic ana; akin to Greek aná up, upon (see ana-)
Can be confusedon on to onto

On

[on]
noun
  1. Biblical name of Heliopolis.

ON

  1. Also ON., O.N. Old Norse.
  2. Ontario, Canada (approved for postal use).

-on

1
  1. a suffix used in the names of subatomic particles (gluon; meson; neutron), quanta (graviton), and other minimal entities or components (cistron; codon; magneton; photon).

Origin of -on

1
probably extracted from ion; cf. proton

-on

2
  1. a suffix used in the naming of inert gaseous elements: neon.

Origin of -on

2
≪ Greek -on, neuter of -os adj. ending
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for on

about, above, adjacent, against, approaching, at, beside, covering, forth, forward, held, near, next, onward, over, touching, toward, upon, with
British Dictionary definitions for on

on

preposition
  1. in contact or connection with the surface of; at the upper surface ofan apple on the ground; a mark on the table cloth
  2. attached toa puppet on a string
  3. carried withI've no money on me
  4. in the immediate vicinity of; close to or along the side ofa house on the sea; this verges on the ridiculous!
  5. within the time limits of a day or datehe arrived on Thursday
  6. being performed upon or relayed through the medium ofwhat's on the television?
  7. at the occasion ofon his retirement
  8. used to indicate support, subsistence, contingency, etche lives on bread; it depends on what you want
    1. regularly taking (a drug)she's on the pill
    2. addicted tohe's on heroin
  10. by means of (something considered as a mode of transport) (esp in such phrases as on foot, on wheels, on horseback, etc)
  11. in the process or course ofon a journey; on strike
  12. concerned with or relating toa tax on potatoes; a programme on archaeology
  13. used to indicate the basis, grounds, or cause, as of a statement or actionI have it on good authority
  14. against: used to indicate oppositionthey marched on the city at dawn
  15. used to indicate a meeting or encounterhe crept up on her
  16. (used with an adjective preceded by the) indicating the manner or way in which an action is carried outon the sly; on the cheap
  17. informal
    1. staked or wagered as a betten pounds on that horse
    2. charged tothe drinks are on me
  18. (usually followed by it) Australian drinking alcoholic liquor
  19. informal, or dialect to the loss or disadvantage ofthe old car gave out on us
adverb (often used as a particle)
  1. in the position or state required for the commencement or sustained continuation, as of a mechanical operationthe radio's been on all night
  2. attached to, surrounding, or placed in contact with somethingthe girl had nothing on
  3. taking placewhat's on tonight?
  4. in a manner indicating continuity, persistence, concentration, etcdon't keep on about it; the play went on all afternoon
  5. in a direction towards something, esp forwards; so as to make progresswe drove on towards London; march on!
  6. on and off or off and on intermittently; from time to time
  7. on and on without ceasing; continually
adjective
  1. functioning; operatingturn the switch to the on position
  2. (postpositive) informal
    1. performing, as on stageI'm on in five minutes
    2. definitely taking placethe match is on for Friday; their marriage is still on
    3. tolerable, practicable, acceptable, etcyour plan just isn't on
    4. (of a person) willing to do something
  3. on at informal naggingshe was always on at her husband
  4. cricket (of a bowler) bowling
noun
  1. cricket
    1. (modifier)relating to or denoting the leg side of a cricket field or pitchthe on side; an on drive
    2. (in combination)used to designate certain fielding positions on the leg sidelong-on; mid-on

Word Origin for on

Old English an, on; related to Old Saxon an, Old High German, Gothic ana

On

noun
  1. the ancient Egyptian and biblical name for Heliopolis

ON

abbreviation for
  1. Old Norse
  2. (esp in postal addresses) Ontario

-on

suffix forming nouns
  1. indicating a chemical substanceinterferon; parathion
  2. (in physics) indicating an elementary particle or quantumelectron; photon
  3. (in chemistry) indicating an inert gasneon; radon
  4. (in biochemistry) a molecular unitcodon; operon

Word Origin for -on

from ion
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for on
prep.

Old English on, unstressed variant of an "in, on, into," from Proto-Germanic *ana "on" (cf. Dutch aan, German an, Gothic ana "on, upon"), from PIE root *an- "on" (cf. Avestan ana "on," Greek ana "on, upon," Latin an-, Old Church Slavonic na, Lithuanian nuo "down from"). Also used in Old English in many places where we would now use in. From 16c.-18c. (and still in northern England dialect) often reduced to o'. Phrase on to "aware" is from 1877. On time is from 1890.

-on

subatomic particle suffix, from ion.

Online Etymology Dictionary, © 2010 Douglas Harper