Sex Education
Bull
A bull is usually a person who engages in sex with someone else’s partner, typically within the context of cuckolding, hotwifing, or other consensual non-monogamy dynamics. The term is most commonly used to describe a third party who plays a sexually dominant or central role in these dynamics, often contrasted with a submissive or voyeuristic partner (sometimes called a cuck, stag, or watcher). A bull can also be a third party in a vixen/stag dynamic where there is no humiliation involved.
While often portrayed as cis men, bulls can be of any gender. What matters is the role, not the body: assertiveness, sexual dominance, and centrality to the scene. The role is often considered to be one that's given to a person by a couple, not self-assigned.
Some people in swinging communities avoid the term because they feel it comes from porn culture or implies arrogance.