1

o

noun, often capitalized, often attributive \ ˈō \
Updated on: 15 Nov 2017

Definition of o

plural o's or os play \ˈōz\
1 a : the 15th letter of the English alphabet
b : a graphic representation of this letter
c : a speech counterpart of orthographic o
2 : a graphic device for reproducing the letter o
3 : one designated o especially as the 15th in order or class
4 : something shaped like the letter O; especially : zero

Examples of o in a Sentence

  1. a word that starts with an o

  2. a word that starts with o

First Known Use of o

before 12th century

o Synonyms

Synonyms
aught, cipher, goose egg, naught (also nought), nil, nothing, zero, oh, zilch, zip
Related Words
blank, void

Other Alphabet Terms


2

o

abbreviation

Definition of o

1 ocean
2 ohm
3 old
4 order
5 over

1

O

interjection

less common spelling of

1 used to express an emotion (such as surprise or desire) or in response to physical stimuli
  • Oh, no! I forgot my key.
  • Oh, don't stop!
2 used in direct address
  • oh, waiter! Will you come here, please?
3 used to express acknowledgment or understanding of a statement
  • Oh, yes. It's one of my favorite cities.
4 used to introduce an example or approximation
  • Their house is about, oh, I'd say four miles from here.

2

O

noun \ ˈō \

Definition of O

: the one of the four ABO blood groups characterized by the absence of antigens designated by the letters A and B and by the presence of antibodies against these antigens

First Known Use of o

1929


3

O

abbreviation

Definition of O

1 offense
2 Ohio
3
[New Latin octarius]
pint

4

O

symbol

Definition of O

oxygen

1

o-

combining form
variants: or oo-

Definition of o-

: egg
  • oology
; specifically : ovum
  • oogonium

Origin and Etymology of o-

Greek ōi-, ōio-, from ōion — more at egg


2

o-

abbreviation

Definition of o-

orth- or ortho-

-o-

affix

Definition of -o-

used as a connective vowel originally to join word elements of Greek origin and now also to join word elements of Latin or other origin
  • speedometer
  • elastomer

Origin and Etymology of -o-

Greek, thematic vowel of many nouns and adjectives in combination


1

-o

noun suffix

Definition of -o

: one that is, has the qualities of, or is associated with
  • bucko

Origin and Etymology of -o

perhaps from 1oh


2

-o

interjection suffix

Definition of -o

in interjections formed from other parts of speech
  • cheerio
  • righto

Origin and Etymology of -o

probably from 1oh



O Defined for English Language Learners

o

noun

Definition of o for English Language Learners

  • : the 15th letter of the English alphabet

  • : the number zero

  • —used as a mark at the end of a letter, an e-mail, etc., to represent a hug


O Defined for Kids

o

noun, often capitalized \ ˈō \

Definition of o for Students

plural o's or os \ˈōz\
1 : the 15th letter of the English alphabet
2 : zero 1

O

Definition of O for Students

  • variant of oh

O.

abbreviation

Definition of O. for Students

Ohio

Medical Dictionary

o-

abbreviation

medical Definition of o-

orth-; ortho-

O

noun \ ˈō \

medical Definition of O

: the one of the four ABO blood groups characterized by the absence of antigens designated by the letters A and B and by the presence of antibodies against these antigens

O

abbreviation

medical Definition of O

1 opening
2
[Latin octarius]
pint used in writing prescriptions

O

symbol

medical Definition of O

oxygen

Learn More about o


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