Why is the ninth month called September?
1580s, "obscene quality," from French obscénité, from Latin obscenitatem (nominative obscenitas) "inauspiciousness, filthiness," from obscenus "offensive" (see obscene). Meaning "a foul or loathsome act" is 1610s. Sense of "an obscene utterance or word" is attested by 1690. Related: Obscenities.
Behavior, appearance, or expression (such as films and books) that violate accepted standards of sexual morality. American courts have long tried to define obscenity but without much success. Some believe, for example, that any depiction of nudity is obscene; others would argue that nudity in itself is not obscene. (See four-letter words and pornography.)