Oh

Full definition of oh

Expression of surprise.Oh! I didn't see you there.
Expression of wonder, amazement, or awe.Oh, wow! That's amazing.
Expression of understanding, recognition, or realization.Oh, so that's how it works.
A word to precede an offhand or annoyed remark.Oh, leave me alone.
A word to precede an added or comment or afterthought.Oh, and don't forget your coat.
An invocation or address (similar to the vocative in languages with noun declension), often with a tern of endearment.Oh, goshOh, baby
Exclamation for drama or emphasis (often poetic).Oh, when will it end?

Sir Walter RaleighOh, by what plots, by what forswearings, betrayings, oppressions, imprisonments, tortures, poisonings, and under what reasons of state and politic subtilty, have these forenamed kings ... pulled the vengeance of God upon themselves ...

Expression of pain. See ouch.Oh! That hurt.
Space filler or extra syllable, especially in (popular) music.oh, oh, oh
(interrogative) Expression of mild scepticism''"You should watch where you're going!" "Oh?"

Particularly in the context of internet conversations, "oh" is sometimes written with additional Os or Hs - for example, oooh or ohhh.

(plural ohs)

the letter O, o (more commonly spelled o)
the digit 0 (especially in representations of speech)My telephone number is four-double-three-two-oh-nine.
An utterance of oh; a spoken expression of surprise, acknowledgement, etc.

Seabert Parsons, The Lost Codex of Palenque (page 240)There were ohs and ahs, and the people twisted about as they looked for her. Then they began to applaud.

1852, Merry's museum and Parley's magazine (volumes 23-24, page 46)A quarter of an hour elapsed, and then, after several rings at the door-bell, a smothered laugh, and a good deal of ohing and ahing, the door was thrown open, and one by one, as they were announced, in came the expected characters.