1. Home
  2. Dictionary
  3. O

Definition of O in English :

Define O in English

O meaning in English

Meaning of O in English

Pronunciation of O in English

O pronunciation in English

Pronounce O in English

O

see synonyms of o

Noun

1. atomic number 8, o, oxygen

a nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gas; constitutes 21 percent of the atmosphere by volume; the most abundant element in the earth's crust

2. o

the 15th letter of the Roman alphabet

3. group o, o, type o

the blood group whose red cells carry neither the A nor B antigens

Example Sentences:
'people with type O blood are universal donors'

WordNet Lexical Database for English. Princeton University. 2010.

O

see synonyms of o
nounWord forms: plural o's, O's or Os
1. 
the 15th letter and fourth vowel of the modern English alphabet
2. 
any of several speech sounds represented by this letter, in English as in code, pot, cow, move, or form
3.  another name for nought
symbol for
1. chemistry
oxygen
2. 
a human blood type of the ABO group
universal donor
3. logic
a particular negative categorial proposition, such as some men are not married: often symbolized as SoP
Compare A, E, I2
abbreviation for
4. Australian slang
offence
exclamation
1.  a variant spelling of oh
2. 
an exclamation introducing an invocation, entreaty, wish, etc
O God!
O for the wings of a dove!
preposition
informal or archaic shortened form of of
a cup o' tea

Collins English Dictionary. Copyright © HarperCollins Publishers

O

see synonyms of o
nounWord forms: plural O's
1.  Popularly
the figure zero; nought
in printed matter, zero is usually differentiated from the letter O, as in this dictionary: “O” is the character used for the letter, “0” is the character used for the number
2. 
a blood type
see also ABO system
interjection
1. 
used in direct address
O Lord!
2. 
used to express surprise, wonder, fear, pain, etc.
now usually oh
3. 
used at the end of a line in some ballads
nounWord forms: plural O's
4. 
an instance of this exclamation
1. 
Ocean
2. 
October
3. 
Ohio
4.  Physics
ohm
5.  Linguistics
Old
OFr
6. 
Ontario
7.  Baseball
out(s)
8.  Pharmacy
pint
oxygen
nounWord forms: plural O's or o's
1. 
the fifteenth letter of the English alphabet: from the Greek omega and omicron, both borrowed from the Phoenician
2. 
any of the speech sounds that this letter represents, as, in English, the vowel ( (oʊ) ; ō) ) of boat, ( (ɑ) ; ä) ) of hot, or ( (ɔ) ; ô) ) of wrong
3. 
a type or impression for o or O
4. 
the fifteenth in a sequence or group
5. 
an object shaped like O
adjective
6. 
of o or O
7. 
fifteenth in a sequence or group
8. 
shaped like O; circular or oval in shape
1. 
octavo
2. 
old
3. 
only
preposition
of1
will-o'-the-wisp

Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by Houghton Mifflin Harcourt. All rights reserved.

O

see synonyms of o
interj.
1. 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).
2. Used to express surprise or strong emotion: "O how I laugh when I think of my vague indefinite riches" (Henry David Thoreau).
The symbol for oxygen.
abbr.
1. Sports
a. offense
b. offensive
2. office telephone number
3. Baseball out
4. outside
5. outstanding
6. Sports overtime
abbr.
1. ocean
2. Ohio
abbr.
1. Latin octarius (pint)
2. also O. octavo
n. pl. o's or O's also os or Os
1. The 15th letter of the modern English alphabet.
2. Any of the speech sounds represented by the letter o.
3. The 15th in a series.
4. Something shaped like the letter O.
5. 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.
6. A zero.
prep.
Informal
Of: lots o' luck; top o' the morning.
Used as a connective to join word elements: acidophilic.
suff.
Used to form an informal, abbreviated, or slang word or variant: ammo.

The American Heritage ® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

WORD OF THE DAY

chiliad

FIND OUT WHAT IT MEANS

Recent Searches