Beta is a slang insult for or describing a man who is seen as passive, subservient, weak, and effeminate.
What is a Omega Male?
noun [countable] a man who chooses not to have a powerful or important role in a social or professional situation. While the alpha male wants to dominate and the beta male just wants to get by, the omega male has either opted out or, if he used to try, given up.
Who is the sigma male?
What is a sigma male? A sigma male is a man within the socio sexual hierarchy who chooses to live his life outside of the normal social dominance hierarchy structures of society.