Lascivious behavior

Lascivious behavior is sexual behavior that is contrary to local moral or other standards of appropriate behavior. In this sense "lascivious" is similar in meaning to "lewd", "lustful", "indecent", "lecherous", "unchaste", "licentious" or "libidinous".

Legal usage

In American legal jargon, lascivious is a semi-technical term indicating immoral sexual actions and in certain cases, words or thoughts. It is often used in the legal description of criminal acts in which some sort of sexual activity is prohibited. The legal definition of the term varies greatly across jurisdictions, and has evolved significantly over time, reflective of current moral values as they relate to sexuality.

For example, in 1896, lascivious cohabitation referred to the now-archaic crime of living with a member of the opposite sex and having premarital sex with him or her. In 2015 the laws of three states of the USA (Florida, Michigan and Mississippi) still considered "lascivious cohabitation" as a crime.