"Button up" is a synonym for "butt on or" and means to fasten or close a garment or object with buttons. "Snap up" is another synonym which refers to fastening or closing using snaps instead of buttons. "Zip up" is a synonym for "butt on or" which means to close or fasten by means of a zipper. "Buckle up" is another synonym which refers to fastening or closing using a buckle. "Tie up" can also be used as a synonym for "butt on or" and refers to fastening or securing something using a tie or knot. Other synonyms for "butt on or" include "clasp," "secure," "latch," "fix," and "attach".