In the laws of Shabbat, Kli SheMelachto LeIsur (A tool whose defined use involves work forbidden) is one of the types of muktzeh, which is - an item that...

"Muktzeh" (items that are set aside and cannot be moved on Shabbat): Kli SheMelachto LeIsur (כלי שמלאכתו לאיסור) - A tool whose defined use involves work forbidden...