Black sheep is used to describe a member of a group that is considered bad or worthless.The term originated from the occasional black sheep which are born into a flock of white sheep. Black wool is considered commercially undesirable because it cannot be dyed.

The term "black sheep" is a metaphorical expression used to describe a member of a group who is considered different, deviant, or wayward compared to the rest of the group. This idiom traces its origins to the world of sheep farming, where the occasional birth of a black sheep into a flock of predominantly white sheep is a natural occurrence.

The symbolism of the black sheep arises from the fact that black wool is perceived as commercially undesirable in the textile industry. Unlike white wool, which can be easily dyed in various colors, black wool does not lend itself well to the dyeing process. As a result, black wool is considered less versatile and, from a commercial standpoint, less valuable.

In a figurative sense, when someone is labeled as the "black sheep" of a family, community, or social group, it implies that they stand out due to their perceived differences or unconventional behavior. The term often carries a negative connotation, suggesting that the individual is seen as an outlier or someone who doesn't conform to the expected norms of the group.

It's important to note that being the black sheep doesn't necessarily indicate wrongdoing on the individual's part; rather, it highlights a divergence from the perceived norms or expectations of the collective. As with many idioms, the metaphorical use of "black sheep" has transcended its agricultural origins and become a widely recognized expression in everyday language.