What part of speech is the word brothers?

The word "brothers" can be two parts of speech depending on how it's used:

* Noun: When referring to multiple male siblings, it's a noun. For example, "My brothers are coming to visit."

* Adjective: It can also be used as an adjective to describe something related to brothers, like "The brothers' club held a meeting."

So, the answer is both noun and adjective.