O definition | Dictionary.com

O, o

[oh]

–noun, plural O's or Os; o's or os or oes.

1.	the fifteenth letter of the English alphabet, a vowel.

2.	any spoken sound represented by the letter O or o, as in box, note, short, or love.

3.	something having the shape of an O.

4.	a written or printed representation of the letter O or o.

5.	a device, as a printer's type, for reproducing the letter O or o.

O

[oh]

interjection, noun, plural O's.

–interjection

1.	(used before a name in direct address, esp. in solemn or poetic language, to lend earnestness to an appeal): Hear, O Israel!

2.	(used as an expression of surprise, pain, annoyance, longing, gladness, etc.)

–noun

3.	the exclamation “O.”

Origin:
1125–75; ME < OF < L ō

O

Old.

2.	Grammar. object.

O

Symbol.

1.	the fifteenth in order or in a series.

2.	the Arabic cipher; zero.

3.	(sometimes lowercase) the medieval Roman numeral for 11. Compare Roman numerals.

4.	Physiology. a major blood group, usually enabling a person whose blood is of this type to donate blood to persons of group O, A, B, or AB and to receive blood from persons of group O. Compare ABO system.

5.	Chemistry. oxygen.

6.	Logic. particular negative.

o'

[uh, oh]

–preposition

1.	an abbreviated form of of, as in o'clock or will-o'-the-wisp.

2.	an abbreviated form of on.

Origin:
ME; by shortening.

O'

a prefix meaning “descendant,” in Irish family names: O'Brien; O'Connor.

Origin:
repr. Ir ó descendant, OIr au

o-

Chemistry.

an abridgment of ortho-.

o-

var. of ob- before m: omission.

o-

var. of oo-: oidium.

-o-

the typical ending of the first element of compounds of Greek origin (as -i- is, in compounds of Latin origin), used regularly in forming new compounds with elements of Greek origin and often used in English as a connective irrespective of etymology: Franco-Italian; geography; seriocomic; speedometer.

Compare -i-.

Origin:
ME (< OF) < L < Gk

-o

1.	a suffix occurring as the final element in informal shortenings of nouns (ammo; combo; condo; limo; promo); -o also forms nouns, usually derogatory, for persons or things exemplifying or associated with that specified by the base noun or adjective (cheapo; pinko; sicko; weirdo; wino).

2.	a suffix occurring in colloquial noun or adjective derivatives, usually grammatically isolated, as in address: cheerio; kiddo; neato; righto.

Origin:
perh. orig. the interjection O, appended to words as in def. 2; as a derivational suffix reinforced by clipped forms of words with -o- as a linking element (e.g., photo, stereo ), by Rom nouns ending in o, and by personal nouns such as bimbo and bozo, of obscure orig.

O.

Ocean.

2.	(in prescriptions) a pint. Origin: < L octārius

octavo.

October.

Ohio.

Old.

Ontario.

Oregon.

o.

1.	pint. Origin: < L octārius

octavo.

off.

old.

only.

order.

7.	Baseball. out; outs.

ob-

a prefix meaning “toward,” “to,” “on,” “over,” “against,” orig. occurring in loanwords from Latin, but now used also, with the sense of “reversely,” “inversely,” to form Neo-Latin and English scientific terms: object; obligate; oblanceolate.

Also, o-, oc-, of-, op-.

Origin:
ME (< OF) < L, repr. ob (prep.); in some scientific terms, < NL, L ob-

Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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Link To O

o or O (ō)

n. pl. o's or O's also os or Os

The 15th letter of the modern English alphabet.
Any of the speech sounds represented by the letter o.
The 15th in a series.
Something shaped like the letter O.
O One of the four major blood groups in the ABO system. Individuals with this blood group have neither A nor B antigens on the surface of their red blood cells, and have both anti-A and anti-B antibodies in their blood serum.
A zero.

O¹ (ō)

interj.

Used before the name of or a pronoun referring to a person or thing being formally addressed: "How can I put it to you, O you who prepare to travel with important matters on your mind?" (Jo Durden-Smith).
Used to express surprise or strong emotion: "O how I laugh when I think of my vague indefinite riches" (Henry David Thoreau).

O²
The symbol for the element oxygen.

O³
abbr.

Baseball out
outstanding

out (out)

adv.

In a direction away from the inside: Let's go out and look at the stars.
Away from the center or middle: The troops fanned out.
1. Away from a usual place: stepped out for a drink of water; went out for the evening.
2. Out of normal position: threw his back out.
3. Out-of-bounds.
4. From inside a building or shelter into the open air; outside: The boy went out to play.
5. In the open air; outside: Is it snowing out?
6. From within a container or source: drained the water out.
7. From among others: picked out the thief in the crowd.
8. To exhaustion or depletion: The supplies have run out.
9. Into extinction or imperceptibility: The fire has gone out.
10. To a finish or conclusion: Play the game out.
11. To the fullest extent or degree: all decked out for the dance.
12. In or into competition or directed effort: went out for the basketball team; was out to win.
13. Into being or evident existence: The new car models have come out.
14. Into public circulation: The paper came out early today.
15. Into disuse or an unfashionable status: Narrow ties have gone out.
16. Into a state of deprivation or loss: voted the incompetent governor out.
1. From inside a building or shelter into the open air; outside: The boy went out to play.
2. In the open air; outside: Is it snowing out?
3. From within a container or source: drained the water out.
4. From among others: picked out the thief in the crowd.
5. To exhaustion or depletion: The supplies have run out.
6. Into extinction or imperceptibility: The fire has gone out.
7. To a finish or conclusion: Play the game out.
8. To the fullest extent or degree: all decked out for the dance.
9. In or into competition or directed effort: went out for the basketball team; was out to win.
10. Into being or evident existence: The new car models have come out.
11. Into public circulation: The paper came out early today.
12. Into disuse or an unfashionable status: Narrow ties have gone out.
13. Into a state of deprivation or loss: voted the incompetent governor out.
1. From within a container or source: drained the water out.
2. From among others: picked out the thief in the crowd.
3. To exhaustion or depletion: The supplies have run out.
4. Into extinction or imperceptibility: The fire has gone out.
5. To a finish or conclusion: Play the game out.
6. To the fullest extent or degree: all decked out for the dance.
7. In or into competition or directed effort: went out for the basketball team; was out to win.
8. Into being or evident existence: The new car models have come out.
9. Into public circulation: The paper came out early today.
10. Into disuse or an unfashionable status: Narrow ties have gone out.
11. Into a state of deprivation or loss: voted the incompetent governor out.
1. To exhaustion or depletion: The supplies have run out.
2. Into extinction or imperceptibility: The fire has gone out.
3. To a finish or conclusion: Play the game out.
4. To the fullest extent or degree: all decked out for the dance.
5. In or into competition or directed effort: went out for the basketball team; was out to win.
6. Into being or evident existence: The new car models have come out.
7. Into public circulation: The paper came out early today.
8. Into disuse or an unfashionable status: Narrow ties have gone out.
9. Into a state of deprivation or loss: voted the incompetent governor out.
In or into a state of unconsciousness: The drug put him out for two hours.
1. Into being or evident existence: The new car models have come out.
2. Into public circulation: The paper came out early today.
3. Into disuse or an unfashionable status: Narrow ties have gone out.
4. Into a state of deprivation or loss: voted the incompetent governor out.
Into view: The moon came out.
Without inhibition; boldly: Speak out.
Into possession of another or others; into distribution: giving out free passes.
1. Into disuse or an unfashionable status: Narrow ties have gone out.
2. Into a state of deprivation or loss: voted the incompetent governor out.
In the time following; afterward: "to gauge economic conditions six months out" (Christian Science Monitor).
Abbr. O Baseball So as to be retired, or counted as an out: He grounded out to the shortstop.
On strike: The auto workers went out when management refused to reduce outsourcing.

adj.

Exterior; external: the out surface of a ship's hull.
Directed away from a place or center; outgoing: the out doorway.
Traveling or landing out-of-bounds.
1. Not operating or operational: The power has been out for a week.
2. Extinguished: The lights were out next door.
Unconscious: was out for an hour during surgery.
Not to be considered or permitted: A taxi is out, because we don't have enough money. From now on, eating candy before dinner is out.
No longer fashionable.
No longer existing in one's possession or supplies: I can't offer you coffee because we're out.
Informal Openly gay, lesbian, or bisexual: an out performer.
Baseball Not allowed to continue to bat or run; retired.

prep.

Forth from; through: He fell out the window.
Beyond or outside of: Out this door is the garage.
Within the area of: The house has a garden out back.

One that is out, especially one who is out of power.
Informal A means of escape: The window was my only out.
Baseball
1. A play in which a batter or base runner is retired.
2. The player retired in such a play.
Sports A serve or return that falls out of bounds in a court game.
Printing A word or other part of a manuscript omitted from the printed copy.

v.   out·ed, out·ing, outs

v.   intr.
To be disclosed or revealed; come out: Truth will out.
v.   tr.

Sports To send (a tennis ball, for example) outside the court or playing area.
To expose (one considered to be heterosexual) as being gay, lesbian, or bisexual: a tabloid article that outed a well-known politican.
Chiefly British To knock unconscious.

interj. Used in two-way radio to indicate that a transmission is complete and no reply is expected.

[Middle English, from Old English ūt; see ud- in Indo-European roots.]

ox·y·gen (ŏk'sĭ-jən)

n. Symbol O
A nonmetallic element constituting 21 percent of the atmosphere by volume that occurs as a diatomic gas, O₂, and in many compounds such as water and iron ore. It combines with most elements, is essential for plant and animal respiration, and is required for nearly all combustion. Atomic number 8; atomic weight 15.9994; melting point -218.4°C; boiling point -183.0°C; gas density at 0°C 1.429 grams per liter; valence 2. See Table at element.

[French oxygène : Greek oxus, sharp, acid; see ak- in Indo-European roots + French -gène, -gen.]
ox'y·gen'ic (-jěn'ĭk) adj., ox'y·gen'i·cal·ly adv., ox·yg'e·nous (ŏk-sĭj'ə-nəs) adj.

The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
Cite This Source

O\ ([=o]). 1. O, the fifteenth letter of the English alphabet, derives its form, value, and name from the Greek O, through the Latin. The letter came into the Greek from the Ph[oe]nician, which possibly derived it ultimately from the Egyptian. Etymologically, the letter o is most closely related to a, e, and u; as in E. bone, AS. b[=a]n; E. stone, AS. st[=a]n; E. broke, AS. brecan to break; E. bore, AS. beran to bear; E. dove, AS. d[=u]fe; E. toft, tuft; tone, tune; number, F. nombre. The letter o has several vowel sounds, the principal of which are its long sound, as in bone, its short sound, as in nod, and the sounds heard in the words orb, son, do (feod), and wolf (book). In connection with the other vowels it forms several digraphs and diphthongs. See Guide to Pronunciation, [sect][sect] 107-129.

2. Among the ancients, O was a mark of triple time, from the notion that the ternary, or number 3, is the most perfect of numbers, and properly expressed by a circle, the most perfect figure. O was also anciently used to represent 11: with a dash over it ([=O]), 11,000.

O\ ([=o]), n.; pl. O's or Oes ([=o]z). 1. The letter O, or its sound. "Mouthing out his hollow oes and aes." --Tennyson.

2. Something shaped like the letter O; a circle or oval. "This wooden O [Globe Theater]". --Shak.

3. A cipher; zero. [R.]

Thou art an O without a figure. --Shak.

O\ ([=o]), a. [See One.] One. [Obs.] --Chaucer. "Alle thre but o God." --Piers Plowman.

O\, interj. An exclamation used in calling or directly addressing a person or personified object; also, as an emotional or impassioned exclamation expressing pain, grief, surprise, desire, fear, etc.

For ever, O Lord, thy word is settled in heaven. --Ps. cxix. 89.

O how love I thy law ! it is my meditation all the day. --Ps. cxix. 97.

Note: O is frequently followed by an ellipsis and that, an in expressing a wish: "O [I wish] that Ishmael might live before thee !" --Gen. xvii. 18; or in expressions of surprise, indignation, or regret: "O [it is sad] that such eyes should e'er meet other object !" --Sheridan Knowles.

Note: A distinction between the use of O and oh is insisted upon by some, namely, that O should be used only in direct address to a person or personified object, and should never be followed by the exclamation point, while Oh (or oh) should be used in exclamations where no direct appeal or address to an object is made, and may be followed by the exclamation point or not, according to the nature or construction of the sentence. Some insist that oh should be used only as an interjection expressing strong feeling. The form O, however, is, it seems, the one most commonly employed for both uses by modern writers and correctors for the press. "O, I am slain !" --Shak. "O what a fair and ministering angel !" "O sweet angel !" --Longfellow.

O for a kindling touch from that pure flame ! --Wordsworth.

But she is in her grave, -- and oh The difference to me ! --Wordsworth.

Oh for a lodge in some vast wilderness ! --Cowper.

We should distinguish between the sign of the vocative and the emotional interjection, writing O for the former, and oh for the latter. --Earle.

O dear, & O dear me! [corrupted fr. F. O Dieu! or It. O Dio! O God! O Dio mio! O my God! --Wyman.], exclamations expressive of various emotions, but usually promoted by surprise, consternation, grief, pain, etc.

Language Translation for : O

Spanish: ¡oh!,

German: oh!,

Japanese: ああ

More Translations »

interj. of fear, surprise, admiration, etc., see oh.

blood type, 1926, originally "zero," denoting absence of A and B agglutinogens.

O

A Nasdaq stock symbol specifying that it is the company's second class of preferred shares.

Investopedia Commentary

Nasdaq-listed securities have four or five characters. If a fifth letter appears, it identifies the issue as other than a single issue of common stock or capital stock.

Main Entry: O
Function: abbreviation
1 opening
2 [Latin octarius] pint —used in writing prescriptions

Main Entry: O
Function: symbol
oxygen

o
The Greek letter omicron. Entries beginning with this character are alphabetized under omicron.

O ¹

The symbol for the element oxygen.

O ²
abbr.
oculus

O
The symbol for oxygen.

oxygen (ŏk'sĭ-jən) Pronunciation Key
Symbol O
A nonmetallic element that exists in its free form as a colorless, odorless gas and makes up about 21 percent of the Earth's atmosphere. It is the most abundant element in the Earth's crust and occurs in many compounds, including water, carbon dioxide, and iron ore. Oxygen combines with most elements, is required for combustion, and is essential for life in most organisms. Atomic number 8; atomic weight 15.9994; melting point -218.4°C; boiling point -183.0°C; gas density at 0°C 1.429 grams per liter; valence 2. See Periodic Table.

Our Living Language : In 1786, the French chemist Antoine Lavoisier coined a term for the element oxygen (oxygène in French). He used Greek words for the coinage: oxy- means "sharp," and -gen means "producing." Oxygen was called the "sharp-producing" element because it was thought to be essential for making acids. Lavoisier also coined the name of the element hydrogen, the "water-producing" element, in 1788. Soon after, in 1791, another French chemist, J. A. Chaptal, introduced the word nitrogen, the "niter-producing" element, referring to its discovery from an analysis of nitric acid.

O character
ASCII code 79, The letter of the alphabet, not to be confused with 0 (zero) the digit.
(1999-02-07)

Latin octarius (pint)
octavo
ohm

old
Oriental (as in personal ads, but usually A, Asian)
out
outstanding

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