A pre-negotiated word that either party (although most commonly the bottom) can use to pause, check-in, or end the scene or play. Safewords function in the same "no" or "stop" might otherwise (and part of their function is allowing the bottom to scream "no" or "stop" as much as they like). Some common safewords are "safeword," and the color system: "red" = stop, "yellow" = check in (some people also use various different colors to mean different things, for instance, "green" = please god don't stop, etc.).