English and Scottish.

There is a significant occurrence of this name in the 1841 Census of Aberdeenshire. It is probably a spelling variant for Kitty [q.v.] and hence a pet name for Katherine/Katharine/Catharine/Catherine notes that Ket, also known as Ketty, occurs five or six times in the 1851 Census of Fearn parish, Ross and Cromarty, Scotland.

It is possible that Ketty has been used as a pet name for Keturah [q.v.] but we have no firm evidence for this.