Definitions
1.nounAn utterance of oh; a spoken expression of surprise, acknowledgement, etc.
2.verbTo utter the interjection oh; to express surprise, etc.
3.interjectionExpression of surprise."Oh! I didn't see you there."
4.interjectionExpression of wonder, amazement, or awe."Oh, wow! That's amazing."
5.interjectionExpression of understanding, affirmation, recognition, or realization."Oh, so that's how it works."
6.interjectionA word to precede an offhand or annoyed remark."Oh, leave me alone."
7.interjectionA word to precede an added comment or afterthought."Oh, and don't forget your coat."
8.interjectionAn invocation or address (similar to the vocative in languages with noun declension), often with a term of endearment.
9.interjectionExclamation for drama or emphasis (often poetic)."Oh, when will it end?"
10.interjectionExpression of pain. See ouch."Oh! That hurt."
11.interjectionSpace filler or extra syllable, especially in (popular) music.
12.interjection(interrogative) Expression of mild scepticism.""You should watch where you're going!" "Oh?""
13.interjectionA word to mark a spoken phrase as imaginary."What if he says "Oh, I need to see your ID"?"