Meaning

noun a round fastener sewn to shirts and coats etc to fit through buttonholes

noun an electrical switch operated by pressing

noun any of various plant parts that resemble buttons

originFrom Middle English boton, botoun, from Old French boton (Modern French bouton), from Old French bouter, boter (“to push; thrust”), ultimately from a Germanic language. Doublet of bouton, Biden, and beat. More at butt.

Etymology from Wiktionary, CC BY-SA 3.0