Indecent describes something that goes against normal standards of good behavior or modesty — most often used about clothing, images, or behavior that shows too much of the body or is sexual in a way thought inappropriate for the situation, like "indecent exposure" (showing private body parts in public, which is illegal in many places). It can also describe behavior that is simply shockingly rude or unfair, as in "an indecent amount of money," meaning an amount so large it seems wrong.