Dominant
Adjective
Being dominant is about exercising influence or control. Governing matters; being in charge. Predisposed to taking over and wanting to maintain power.
Noun
In BDSM, a dominant is a person who takes the dominant role for the duration of a scene or is a dominant partner within a power exchange relationship.
This term can be associated with being on the giving or controlling end of bondage, discipline or sadism but a dominant's activities might not include any of these.
A dominant need not be a sexual top; for example, a female dominant may command her submissive to penetrate her.
The term dominant as a noun is mostly synonymous with Dom but some people use it more widely to denote anyone disposed to be dominant and would therefore say that a dominant might be a Top, a Dom or a Master.
Note that some partners like to switch roles from one encounter to the other, or even during a single encounter, depending on mood and preference. See switch.