oh-ho

The word "oh-ho" is a compound interjection, a playful and emphatic variant of the simple exclamation "oh". Its formation follows a common pattern in English where a base word is repeated with a slight phonetic alteration, often a change in the vowel sound, to create a new expressive term. The element "ho" itself has a long history as an exclamation to attract attention or express surprise, dating back to Middle English. Over time, "oh-ho" crystallized as a specific interjection used to convey a nuanced reaction, such as sudden discovery, smug satisfaction, or teasing accusation, its tone heavily dependent on context and delivery.

This is a reduplicative interjection formed by the repetition and variation of the exclamation "oh". The second element "ho" is an archaic or variant exclamation.