Antonyms of adj irreproachable

1 sense of irreproachable

Sense 1
blameless, inculpable, irreproachable, unimpeachable -- (free of guilt; not subject to blame; "has lived a blameless life"; "of irreproachable character"; "an unimpeachable reputation")

INDIRECT (VIA innocent) -> guilty -- (responsible for or chargeable with a reprehensible act; "guilty of murder"; "the guilty person"; "secret guilty deeds")

Similarity of adj irreproachable

1 sense of irreproachable

Sense 1
blameless, inculpable, irreproachable, unimpeachable -- (free of guilt; not subject to blame; "has lived a blameless life"; "of irreproachable character"; "an unimpeachable reputation")
       => innocent (vs. guilty), guiltless, clean-handed -- (free from evil or guilt; "an innocent child"; "the principle that one is innocent until proved guilty")