Antonyms of adj punctual

1 sense of punctual

Sense 1
punctual (vs. unpunctual) -- (acting or arriving or performed exactly at the time appointed; "she expected guests to be punctual at meals"; "he is not a particularly punctual person"; "punctual payment")

unpunctual (vs. punctual) -- (not punctual; after the appointed time)
        => behindhand -- (behind schedule; "was behindhand with the rent")
        => belated, late, tardy -- (after the expected or usual time; delayed; "a belated birthday card"; "I'm late for the plane"; "the train is late"; "tardy children are sent to the principal"; "always tardy in making dental appointments")
        => benighted, nighted -- (overtaken by night or darkness; "benighted (or nighted) travelers hurrying toward home")
        => last-minute -- (just before a deadline; at the last minute; "last-minute arrangements")

Similarity of adj punctual

1 sense of punctual

Sense 1
punctual (vs. unpunctual) -- (acting or arriving or performed exactly at the time appointed; "she expected guests to be punctual at meals"; "he is not a particularly punctual person"; "punctual payment")
       => prompt -- (according to schedule or without delay; on time; "the train is prompt")
       => timely -- (before a time limit expires; "the timely filing of his income tax return")