Dancing in an erotic manner where the intent is to get your partner sexually stimulated, perhaps to the point of orgasm. Surreptitious touching of erogenous zones is a key technique of floorplay. Variant of the word forplay.
Bill and Joanna had not yet had sex, which made the floorplay all the more delicious. When nobody was looking, He would grind his pelvic bone against her crotch and slide his hand down to her beautiful bottom.