chemsex Share definition Flag chemical (drugs) + sex. it means having sex while being high on drugs chemsex is fantastic. He smoked weed and fucked me all night, I was also high on MDMA chemsex by Lil GM January 18, 2020 Word of the Day on September 1, 2025 0 0 Get merch Get the chemsex mug. Buy Now — $32.95 See more merch