Antonyms of adj chock-a-block

1 sense of chockablock

Sense 1
chockablock (predicate), chock-full, chockful, choke-full, chuck-full, cram full -- (packed full to capacity; "chowder chockablock with pieces of fish")

INDIRECT (VIA full) -> empty -- (holding or containing nothing; "an empty glass"; "an empty room"; "full of empty seats"; "empty hours")

Similarity of adj chock-a-block

1 sense of chockablock

Sense 1
chockablock (predicate), chock-full, chockful, choke-full, chuck-full, cram full -- (packed full to capacity; "chowder chockablock with pieces of fish")
       => full (vs. empty) -- (containing as much or as many as is possible or normal; "a full glass"; "a sky full of stars"; "a full life"; "the auditorium was full to overflowing")

Synonyms of adv chock-a-block

1 sense of chock-a-block

Sense 1
chock, chock-a-block -- (as completely as possible; "it was chock-a-block full")