Kink

Kink is the umbrella; BDSM is one neighborhood under it. Wikipedia defines kink as the use of sexual practices, concepts, or fantasies that fall outside conventional norms, with the contrast term being "vanilla." The boundary moves with culture — oral sex, sex toys, and threesomes were each treated as kink in living memory and now read as standard for many people — which is why the term is consistently relative rather than diagnostic.

Within sexology the umbrella is broad enough to include BDSM, fetish play, role-play, exhibitionism, voyeurism, sensation play, and a long tail of more specific interests. A 2016 Quebec study summarized in the Wikipedia entry found that nearly half of respondents reported interest in at least one non-conventional category, and roughly a third had acted on it, which puts kink solidly in the realm of typical adult sexuality rather than a fringe behavior.

For the lifestyle community, the practical importance of the word is filtering. A "kinky" tag on a profile signals openness to power exchange, fetish wear, or specific fantasies on top of standard swinging. Kink communities have their own etiquette layer — explicit negotiation, formal scenes, designated dungeons, aftercare conventions — that sometimes maps onto lifestyle play and sometimes stays separate. Many lifestyle resorts and takeover events now include a kink-friendly room or themed night specifically because the audiences overlap; the vocabulary, not the activity, is what changes between the two communities.