Oh

[oh] /oʊ/

interjection
1.
(used as an expression of surprise, pain, disapprobation, etc.)
2.
(used in direct address to attract the attention of the person spoken to):
Oh, John, will you take these books?
noun, plural oh’s, ohs.
3.
the exclamation “oh.”.
verb (used without object)
4.
to utter or exclaim “oh.”.
[oh] /oʊ/
noun
1.
Sadaharu [sah-duh-hahr-oo] /ˌsɑ dəˈhɑr u/ (Show IPA), born 1940, Chinese baseball player and manager in Japan.
1.
Ohio (approved especially for use with zip code).
/əʊ/
interjection
1.
an exclamation expressive of surprise, pain, pleasure, etc
sentence connector
2.
an expression used to preface a remark, gain time, etc: oh, I suppose so
abbreviation
1.
Ohio

1530s, interjection expressing various emotions, a common Indo-European word (e.g. Old French ô;, oh; Latin o, oh; Greek o; Old Church Slavonic and Lithuanian o; Gothic, Dutch, German o; Old Irish a; Sanskrit a), but not found in Old English, which translated Latin oh with la or eala.

The present tendency is to restrict oh to places where it has a certain independence, & prefer o where it is proclitic or leans forward upon what follows …. [Fowler]

Often extended for emphasis, e.g. Oh, baby, stock saying from c.1918; oh, boy (1910); oh, yeah (1924). Reduplicated form oh-oh as an expression of alarm or dismay is attested from 1944. Oh-so “so very” (often sarcastic or ironic) is from 1922. Oh yeah? “really? Is that so?” attested from 1930.

1.
off hand
2.
Ohio
3.
open house (real estate)