The Collaborative International Dictionary
sivvens
Sibbens \Sib"bens\, n. [Etymol. uncertain.] (Med.) A contagious disease, endemic in Scotland, resembling the yaws. It is marked by ulceration of the throat and nose and by pustules and soft fungous excrescences upon the surface of the body. In the Orkneys the name is applied to the itch.
Wiktionary
sivvens
n. (alternative form of sibbens English)