variety of amorous impulses Mel White. Word forms: plural libertines. If you refer to someone as a libertine, you mean that they are sexually immoral and do not. Libertine Definition of Libertine Libertine definition, a person who is morally or sexually unrestrained. Other words shift wildly in rank and volume, often as a ripple effect of a news item. Libertine définition, signification, ce qu est libertine : a person, usually a man, who lives in a way that is not moral, having sexual relationships. A libertine is someone who lives life unencumbered by morals. By the nineteenth century, the word became strongly associated with immorality and.