Jam-packed is an adjective that means filled or crowded tightly with things or people. The antonyms for jam-packed are spacious, hollow, empty, and deserted. Spacious is the opposite of jam-packed as it refers to a large area that is uncluttered and offers plenty of room. Hollow describes something that is empty on the inside, and therefore doesn't take up space. Empty and deserted refer to a place that is uninhabited or unoccupied. These words are commonly used to describe an area or venue that is not busy or has a low turnout. They are the complete opposite of jam-packed.