Antonyms of adj needful

1 sense of needful

Sense 1
needed, needful, required, requisite -- (necessary for relief or supply; "provided them with all things needful")

INDIRECT (VIA necessary) -> unnecessary, unneeded -- (not necessary)

Similarity of adj needful

1 sense of needful

Sense 1
needed, needful, required, requisite -- (necessary for relief or supply; "provided them with all things needful")
       => necessary (vs. unnecessary) -- (absolutely essential)