Antonyms of adv impermissibly

1 sense of impermissibly

Sense 1
impermissibly -- (not permissibly; "the radon level in the basement was impermissibly high")
       Antonym of permissibly (Sense 1)
      => permissibly, allowably -- (in a permissible manner)

Synonyms of adv impermissibly

1 sense of impermissibly

Sense 1
impermissibly -- (not permissibly; "the radon level in the basement was impermissibly high")