Chock full is an idiom that means completely full, jam-packed, or overflowing. The opposite of chock full is void or devoid. Void means empty, lacking, or containing nothing. Therefore, if something is void, it does not contain anything or is completely empty. Likewise, devoid means lacking, without, or free from something. In other words, if something is devoid of something, it means it has none of that particular thing. Empty, barren, bare, vacant, unoccupied, and unfilled are some other antonyms of chock full. These words indicate that something is not full or does not contain anything.