Lust or lechery (Latin: luxuria (carnal)) is intense longing. It is usually thought of as intense or unbridled sexual desire, which may lead to fornication (including adultery), rape, bestiality, and other sinful and sexual acts; oftentimes, however, it could also mean other forms of unbridled desire, such as for money, or power. Henry Edward Manning explains that the impurity of lust transforms one into "a slave of the devil".

Dante defined lust as the disordered love for individuals. It is generally thought to be the least serious capital sin as it is an abuse of a faculty that humans share with animals and sins of the flesh are less grievous than spiritual sins. In Dante's Purgatorio, the penitent walks within flames to purge himself of lustful thoughts and feelings. Unforgiven souls guilty of lust are also eternally blown about in restless hurricane-like winds symbolic of their own lack of self-control of their lustful passions in earthly life and as shown in Dante's Inferno.[