CONCUPISCENCE, n. L., to covet or lust after, to desire or covet. Lust; unlawful or irregular desire of sexual pleasure. In a more general sense, the coveting of carnal things, or an irregular appetite for worldly good; inclination for unlawful enjoyments.
We know even secret concupiscence to be sin.
Sin, taking occasion by the commandment, wrought in me all manner of concupiscence. Romans 7.