Definition - What does Safeword mean?
During sexual role playing, particularly BDSM play, a safeword is used when one participant is uncomfortable and wants the scene to be less intense or stop altogether. Safewords should be established before a role-playing scene begins. All participants should be aware and respectful of of those words.
Kinkly explains Safeword
The word "stop" may seem like an obvious safeword, but during BDSM play it's not uncommon for this word to be used to enhance the sexual pleasure or mood. Instead, the best safewords are words or phrases that are easy to say and would not normally be spoken during role playing. The universal safewords red, green, and yellow mean stop, go, and slow down.