A bottom is a partner who takes the role of receiver in such acts as bondage, discipline, sadomasochism or humiliation in BDSM scenes or interactions. A 'Top' performs acts such as these upon the bottom. A bottom may be male or female.
The bottom is quite often the partner who is giving instructions, i.e., they direct the Top as to what and when things are to happen to them. A Bottom who only ever receives instructions, especially if more than just a of a sensory nature, is normally called a sub. If they obey all safe commands from the Top, they are often termed a slave (though they may not be).
The term originates from a more general use of the word, especially among the gay male community, to mean receptive partner. However, a BDSM bottom need not be sexually bottom and activities between a Top and Bottom might or might not include sex.. A bottom might also be a masochist. It is possible for two partners to switch roles from one encounter to the other, or even during a single encounter, depending on mood and preference. See switch. The relationship between a bottom and their Top may be very transitory or can be permanent. Some bottoms are married to their Top.
In order to explore BDSM, it is essential for a bottom to communicate well so that the Top can be responsive to their needs, feelings, and limits. Otherwise the scene can be ruined, being simply painful or inconvenient rather than erotic. Failure to choose a trustworthy top can be very dangerous, and even a trustworthy but overzealous top can inflict severe pain or injury by failing to pay attention to the bottom.
In Japanese bondage, a bottom is referred to as uke, a term from martial arts.