Bell-bottoms are trousers whose legs stay fairly straight to the knee and then open out, wider and wider, down to the hem — like the mouth of a bell. Sailors wore a version long before high-street fashion did, because a wide hem is easy to roll up on a wet deck. In the 1960s and 1970s the shape walked into ordinary shops and onto disco floors, and English still reaches for bell-bottoms when the flare is strong and theatrical, not a timid little widening. In Britain people also say flares, which is the same idea in a shorter word. Though actually, bootcut is a quieter cousin: it only opens a little at the foot, so it can sit over a boot. Bell-bottoms make a rounder, louder statement. The word is almost always plural, like trousers itself: you buy bell-bottoms, you wear them. Saying 'a bell-bottom' usually means one leg, not the garment. They go in and out of fashion; when they come back, older speakers still hear 1970s in the word, even on a new pair.