butt on (Noun) — A round fastener sewn to shirts and coats etc to fit through buttonholes.
butt on (Noun) — An electrical switch operated by pressing. ex. "the elevator was operated by push buttons"
butt on (Noun) — Any of various plant parts that resemble buttons.
butt on (Noun) — A round flat badge displaying information and suitable for pinning onto a garment. ex. "they passed out campaign buttons for their candidate"
butt on (Noun) — A female sexual organ homologous to the penis.
butt on (Noun) — A device that when pressed will release part of a mechanism.
butt on (Noun) — Any artifact that resembles a button.
butt on (Noun) — (computing) an on-screen control that can be clicked on to invoke a particular function.
butt on (Verb) — Lie adjacent to another or share a boundary. ex. "Canada butts on the U.S."
butt on (Verb) — Provide with buttons. ex. "button a shirt"
butt on (Verb) — Fasten with buttons. ex. "button the dress"