Having legs that flare out at the bottom: bell-bottom trousers. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "bell-bottom" in a sentence
"And how he used to dress, said Sarah, apparently referring to his bell-bottom years."
"His music is still swinging — itself no longer an asset by 1971 — but Prima himself, dressed in a blue bell-bottom suit and sporting a Beatle haircut, seems like a man who has outlived his moment."
"As for jeans, the backlash has begun on skinny jeans in women's fashion — bell-bottom versions have made frightening appearances on runways — and will follow in men's as well, though hopefully in a more understated way."