button-down

collar collar with ends that are fastened to the shirt with buttons 两端有钮扣扣在衬衫上的衣领.

but for, butane, butch, butcher, butcher's shop, butchery, butler, butt, butter, butter-bean, butter-fingers, buttercup, butterfly, buttermilk, butterscotch, buttery, buttock, button, button mushroom, button up, buttoned up, buttonhole, buttonhook, buttress, buxom, buy, buy off, buy out, buy up, buyer, buzz, buzz off, buzz-word, buzzard, buzzer, by, by accident, by air, by all means, by all nerves,