Antonyms of adj 31st

1 sense of 31st

Sense 1
thirty-first, 31st -- (coming next after the thirtieth in position)

INDIRECT (VIA ordinal) -> cardinal -- (being or denoting a numerical quantity but not order; "cardinal numbers")

Similarity of adj 31st

1 sense of 31st

Sense 1
thirty-first, 31st -- (coming next after the thirtieth in position)
       => ordinal (vs. cardinal) -- (being or denoting a numerical order in a series; "ordinal numbers"; "held an ordinal rank of seventh")