buttass🔊advEtymology From butt + ass.1Canada, US, Mildly, Slang, Vulgar Synonym of very.At least he isn't butt-ass ugly. He was probably the shit during his time. Look at him in his multi-colored, polyester suit. He's sharper than a tack.2015, Teresa D. Patterson, Wolf in the Pulpit, page 194: