The term "saline" is generally used in the context of salty water or a solution with a high salt content. In the context of adult content, it may refer to a scenario involving saltwater or a fetish for such content. It could be used to describe a scene where a person (or people) engage in sexual activity while submerged in, or using saltwater as part of their activity. This tag might also indicate that there is some form of water play or wet and messy fetish involved in the scene.