Dictionary.com

o'

[ uh, oh ]
/ ə, oʊ /

preposition

a shortened form of of, as in o'clock or will-o'-the-wisp.
Chiefly Dialect. a shortened form of on.

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Origin of o'

From Middle English; by shortening

Definition for o' (2 of 15)

O1

or o

[ oh ]
/ oʊ /

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

the fifteenth letter of the English alphabet, a vowel.
any spoken sound represented by the letter O or o, as in box, note, short, or love.
something having the shape of an O.
a written or printed representation of the letter O or o.
a device, as a printer's type, for reproducing the letter O or o.

Definition for o' (3 of 15)

O2
[ oh ]
/ oʊ /

interjection

(used before a name in direct address, especially in solemn or poetic language, to lend earnestness to an appeal): Hear, O Israel!
(used as an expression of surprise, pain, annoyance, longing, gladness, etc.)

noun, plural O's.

the exclamation “O.”

Origin of O

2
First recorded in 1125–75; Middle English, from Old French, from Latin ō

WORDS THAT MAY BE CONFUSED WITH O

O , oh, owe

Definition for o' (4 of 15)

O3

Grammar. object (def. 7).
Old.

Definition for o' (5 of 15)

O4

Symbol.

the fifteenth in order or in a series.
the Arabic cipher; zero.
(sometimes lowercase) the medieval Roman numeral for 11.Compare Roman numerals.
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.
Chemistry. oxygen.
Logic. particular negative.

Definition for o' (6 of 15)

O'

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

Origin of O'

Representing Irish ó descendant, Old Irish au

Definition for o' (7 of 15)

o-1

Chemistry.

an abridgment of ortho-.

Definition for o' (8 of 15)

o-2

variant of ob- before m:omission.

Definition for o' (9 of 15)

o-3

variant of oo-: oidium.

Definition for o' (10 of 15)

-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 of -o-

Middle English (<Old French ) <Latin <Greek

Definition for o' (11 of 15)

-o

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

Origin of -o

Perhaps originally 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 origin

Definition for o' (12 of 15)

o.1

pint.

Origin of o.

1
From the Latin word octārius

Definition for o' (13 of 15)

o.2

octavo.
off.
old.
only.
order.
Baseball. out; outs.

Definition for o' (14 of 15)

O.1

(in prescriptions) a pint.

Origin of O.

1
From the Latin word octārius

Definition for o' (15 of 15)

O.2

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for o' (1 of 8)

o

O

/ (əʊ) /

noun plural o's, O's or Os

the 15th letter and fourth vowel of the modern English alphabet
any of several speech sounds represented by this letter, in English as in code, pot, cow, move, or form
another name for nought

British Dictionary definitions for o' (2 of 8)

o'
/ (ə) /

preposition

informal, or archaic shortened form of of a cup o' tea

British Dictionary definitions for o' (3 of 8)

O1

symbol for

chem oxygen
a human blood type of the ABO groupSee universal donor
logic a particular negative categorial proposition, such as some men are not married: often symbolized as SoPCompare A, E, I 2

abbreviation for

Australian slang offence

Word Origin for O

(for sense 3) from Latin (neg) o I deny

British Dictionary definitions for o' (4 of 8)

O2
/ (əʊ) /

interjection

a variant spelling of oh
an exclamation introducing an invocation, entreaty, wish, etcO God!; O for the wings of a dove!

British Dictionary definitions for o' (5 of 8)

O'-

prefix

(in surnames of Irish Gaelic origin) descendant ofO'Corrigan

Word Origin for O'-

from Irish Gaelic ó, ua descendant

British Dictionary definitions for o' (6 of 8)

o-

prefix

short for ortho- (def. 4)

British Dictionary definitions for o' (7 of 8)

-o-

connective vowel

used to connect elements in a compound wordchromosome; filmography Compare -i-

Word Origin for -o-

from Greek, stem vowel of many nouns and adjectives in combination

British Dictionary definitions for o' (8 of 8)

-o

suffix

forming informal and slang variants and abbreviations, esp of nounswino; lie doggo; Jacko

Word Origin for -o

probably special use of oh
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

Medical definitions for o' (1 of 4)

O 22

abbr.

oculus

Medical definitions for o' (2 of 4)

O 11

The symbol for the elementoxygen

Medical definitions for o' (3 of 4)

o-

abbr.

ortho- (often italic)

Medical definitions for o' (4 of 4)

-o-

Used as a connective to join word elements:acidophilic.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for o'

O

The symbol for oxygen.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.