Safe word

[Justin Bieber]

An agreed upon word, or set of words, used in any kind of sexual activity, not limited to [BDSM] play, that is uttered by any participant to [communicate] that they want the activity to be modified.
Sexual safe words could also be called sexual [trust] words, and theyre an especially good idea in any kind of [sex play] that is exploratory and/or new to any participant.
Different safe words can be created and agreed upon to mean different things, such as, [stop] everything, right now!, slow down, back off!, dont stop!, etc.
Safe words should be ones that a participant isnt likely to use as part of the play. They can be complete code, like Tibet (stop), Chicago (slow down), and [Glesga] (dont stop), or more obvious, like red, yellow, and green.
No kind of sex should EVER be forced on anyone- thats called [rape]! (which is totally different than indulging in an agreed upon [rape fetish])- and the basic idea of safe words is to prevent rape from happening accidentally.
Safe words make for [hot sex]!

[Hina Muqadas]

In BDSM community, a word (usually irrelevant and strange in the context of the sexual situation) agreed by the participating parties to [cease] [the activity]. This is so that the submissive partner(s) can say stop and no as often as they want during the session and use [the safe] word when they actually mean it.

[Rihanna]

A word used as a signal to stop a sexual act, usually if its too rough (ex: spankings, [rough sex], anal sex)
WARNING! DO NOT in ANY given circumstances EVER use [positive feedback] as a [safe word]!! Some examples are Daddy, yes!, Please!, or More! You may think that youre going to remember that you should slow down, but cmon lets get real here. Its going to get you even more excited.
Just be careful about what you agree upon.

[GarryDrold]

In the practice of [sado-masochism], a safe word, is [an agreed upon] word uttered by the recipient masochist, when he/she can no longer tollerate any more pain administered by the [sadist], during a session. Maybe also be used, to indicate they may need a temporary break in said session.