O

Pronunciation (US):

(GB):

IPA (US):

 Dictionary entry overview: What does O mean? 

• O (noun)
  The noun O has 3 senses:

1. 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. the 15th letter of the Roman alphabet

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

  Familiarity information: O used as a noun is uncommon.

 Dictionary entry details 

• O (noun)

Sense 1

Meaning:

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

Classified under:

Nouns denoting substances

Synonyms:

atomic number 8; O; oxygen

Hypernyms ("O" is a kind of...):

chemical element; element (any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter)

gas (a fluid in the gaseous state having neither independent shape nor volume and being able to expand indefinitely)

Hyponyms (each of the following is a kind of "O"):

liquid oxygen; LOX (a bluish translucent magnetic liquid obtained by compressing gaseous oxygen and then cooling it below its boiling point; used as an oxidizer in rocket propellants)

Holonyms ("O" is a substance of...):

air (a mixture of gases (especially oxygen) required for breathing; the stuff that the wind consists of)

H2O; water (binary compound that occurs at room temperature as a clear colorless odorless tasteless liquid; freezes into ice below 0 degrees centigrade and boils above 100 degrees centigrade; widely used as a solvent)

ozone (a colorless gas (O3) soluble in alkalis and cold water; a strong oxidizing agent; can be produced by electric discharge in oxygen or by the action of ultraviolet radiation on oxygen in the stratosphere (where it acts as a screen for ultraviolet radiation))

Sense 2

Meaning:

The 15th letter of the Roman alphabet

Classified under:

Nouns denoting communicative processes and contents

Hypernyms ("O" is a kind of...):

alphabetic character; letter; letter of the alphabet (the conventional characters of the alphabet used to represent speech)

Holonyms ("O" is a member of...):

Latin alphabet; Roman alphabet (the alphabet evolved by the ancient Romans which serves for writing most of the languages of western Europe)

Sense 3

Meaning:

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

Classified under:

Nouns denoting body parts

Synonyms:

group O; O; type O

Context example:

people with type O blood are universal donors

Hypernyms ("O" is a kind of...):

blood group; blood type (human blood cells (usually just the red blood cells) that have the same antigens)

 Context examples 

“What o’clock was it?” she asked.

(The Return of Sherlock Holmes, by Sir Arthur Conan Doyle)

If this ain't, said Mr. Peggotty, sitting down among us by the fire, the brightest night o' my life, I'm a shellfish—biled too—and more I can't say.

(David Copperfield, by Charles Dickens)

O, sir, cried Poole, do you think I do not know my master after twenty years?

(The Strange Case Of Dr. Jekyll And Mr. Hyde, by Robert Louis Stevenson)

On that evening the horses had been exercised and watered as usual, and the stables were locked up at nine o’clock.

(The Memoirs of Sherlock Holmes, by Sir Arthur Conan Doyle)

“Three goes o' rum! Why, shiver my timbers, if I hadn't forgotten my score!”

(Treasure Island, by Robert Louis Stevenson)

Strange and sudden change in Renfield last night. About eight o'clock he began to get excited and sniff about as a dog does when setting.

(Dracula, by Bram Stoker)

The face of Jim O’Brien, a Mastodon King and old-time comrade, caught his eyes.

(The Call of the Wild, by Jack London)

He had been there since one o’clock.

(His Last Bow, by Sir Arthur Conan Doyle)

I won't start out till ten o'clock.

(Martin Eden, by Jack London)

Served 'm right. You said so yourself, Mr. Scott. He tried to take White Fang's meat, an' he's dead-O.

(White Fang, by Jack London)