Definition of ohmigosh in English:
ohmigosh
(also ohmygosh)
exclamation ˌəʊmʌɪˈɡɒʃˈəʊmʌɪˌɡɒʃ
North American informal Expressing excitement, surprise, dismay, fear, etc.
Origin
1920s. Altered spelling of oh my gosh, apparently intended to represent a rapid or emphatic pronunciation.