O, o

/oh/, n., pl. O's or Os; o's or os or oes.

1. the fifteenth letter of the English alphabet, a vowel.

2. any spoken sound represented by the letter O or o, as in box, note, short, or love.

3. something having the shape of an O.

4. a written or printed representation of the letter O or o.

5. a device, as a printer's type, for reproducing the letter O or o.