Jam-packed is a term used to describe a space or container that is filled to its maximum capacity. Antonyms for this term include empty, spacious, and vacant. These words convey the opposite idea of jam-packed, meaning something that is not full or is able to accommodate more. An empty or vacant room is free of any objects, making it the opposite of jam-packed. Alternatively, a spacious room provides ample room for movement and does not feel cramped. Therefore, opposed to jam-packed, which conveys a sense of suffocation or lack of space, antonyms for it suggest that there is enough space to breathe and move around.