Antonyms of adj creditable

1 sense of creditable

Sense 1
creditable -- (worthy of often limited commendation; "the student's effort on the essay--though not outstanding--was creditable")

INDIRECT (VIA worthy) -> unworthy -- (lacking in value or merit; "dispel a student whose conduct is deemed unworthy"; "unworthy of forgiveness")

Similarity of adj creditable

1 sense of creditable

Sense 1
creditable -- (worthy of often limited commendation; "the student's effort on the essay--though not outstanding--was creditable")
       => worthy (vs. unworthy) -- (having worth or merit or value; being honorable or admirable; "a worthy fellow"; "a worthy cause")