Adjective: impermissible ,im-pu(r)'mi-su-bul
- Not permitted
"impermissible behaviour"
- Not allowable
"The use of cell phones during the exam was impermissible"
See also: forbidden, inadmissible, intolerable, out, prohibited, proscribed, taboo, tabu [archaic], unbearable, unendurable, unmentionable, untouchable, verboten
Antonym: allowable