The term 'leftover part' can be described by three different words: REST (4 letters), RESIDUE (7 letters), and SCRAP (5 letters). REST is a verb meaning to take a break or pause from activity. RESIDUE is a noun meaning the remainder of something after the main part has been used or removed. SCRAP is a noun meaning a small piece of something that is left over after the main part has been used or removed. All three words refer to something that is left over after the main part has been used or removed.