butterbutt

== English == === Alternative forms === butter butt, butter-butt === Etymology === From butter +‎ butt. === Noun === butterbutt (plural butterbutts) (colloquial) The yellow-rumped warbler (Setophaga coronata), a North American bird species with a conspicuous yellow rump. (Australia, colloquial) The yellow-rumped thornbill (Acanthiza chrysorrhoa), an Australian bird species with a conspicuous yellow rump.