verb. To leave the erect, sexually aroused state.

verb. To lose one's sexual arousal: to experience the detumescence of one's sexual organs.

verb. To cause (a person) to detumesce: to induce detumescence.

"Although it is not at all uncommon for such lovers, who have fully learned this art, to go to sleep thus, in each other's arms, their sex organs united; and, in this position, have the organs detumesce, the penis grow limp and slip out of the vagina of its own accord, while the vagina also grows small and the clitoris subsides."

detumescence  detumescent  

demesne