تعریف و معنای "the bee's knees"

What is the origin of the idiom "the bee's knees" and when to use it?

The origin of the idiom "the bee's knees" is uncertain, but it is believed to have emerged in the 1920s in the United States during the era of flappers and jazz. The phrase is mostly used to describe something or someone as excellent, outstanding, or of very high quality. It gained popularity as part of the slang vocabulary during the Roaring Twenties, a time of societal and cultural change, where it became synonymous with the latest trends, fashionable items, or anything considered to be top-notch.