firmly UK /ˈfɜːmli/US /ˈfɝmli/ adverb3 •In a firm or definite or strong manner.She corrected him firmly but gently. •Securely.Tie the rope firmly to the post. •Definitively.This was widely interpreted to mean that slavery was once more firmly illegal in England. — 2018 formsfirmlier · more firmly · firmliest · most firmly