"Lascivious" is a word synonymous with lustful or lewd.
In American legal jargon, lascivious is a semi-technical term indicating immoral sexual thoughts or actions. It is often used in the legal description of criminal acts in which some sort of sexual activity is prohibited to differentiate that activity from "innocent" conduct. It is often used as one of several adjectives to describe pornography as compared to non-pornographic depictions of sex or sexual themes.
In |American legal jargon mailing lascivious matter is prohibited thus:
Every obscene, lewd, lascivious, indecent, filthy or vile article, matter, thing, device, or substance ... [i]s declared to be nonmailable matter and shall not be conveyed in the mails or delivered from any post office or by any letter carrier.
Lascivious is not limited to pornography, however. For example, lascivious cohabitation refers to a mostly archaic crime of living with a member of the opposite sex, and having sexual intercourse with him or her without first entering a legal or religious marriage. The legal term "Lewd & Lascivious", is connected to a crime of which occurs when an Adult has sexual contact with an underage Child, most definitions of this crime are defined as Lewd & Lascivious acts with an Child under the age of (18), Though the extent of this crime covers Forcible Rape, Penetration with foreign objects, the California Penal Code Section is 288, research will show that after an initial annoyance or molest the crime that follows is the more serious act of "lewd & lascivious acts", sexual abuse.