O — synonyms, definition

1. o (Noun)

atomic number 8 group O oxygen type O

o (Noun) — The blood group whose red cells carry neither the A nor B antigens. ex. "people with type O blood are universal donors"

o (Noun) — The 15th letter of the Roman alphabet.

o (Noun) — A nonmetallic bivalent element that is normally a colourless, odourless, tasteless, nonflammable diatomic gas; constitutes 21 percent of the atmosphere by volume; the most abundant element in the earth's crust.

alphabetic character blood group blood type chemical element element gas letter letter of the alphabet liquid oxygen lox H2O Latin alphabet Roman alphabet air ozone water

2. o (Interjection)

o (Interjection) — Used to express surprise. ex. "O, it was only a dollar last time I was here!"