O
| Pronunciation (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)
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))
Meaning:
The 15th letter of the Roman alphabet
Classified under:
Nouns denoting communicative processes and contents
Synonyms:
letter o; O
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)
Meaning:
The blood group whose red cells carry neither the A nor B antigens
Classified under:
Nouns denoting body parts
Synonyms:
group O; type O; 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)
