1) Forbidden 2) French word used in English 3) Intolerable 4) Not allowable 5) Not permissible or allowable 6) Not permitted 7) Prohibited 8) Proscribed 9) Taboo 10) Tabu 11) Unallowable 12) Unmentionable 13) Untouchable 14) Verboten 1) Forbidden 2) Inadmissible 3) Intolerable 4) Prohibited 5) Proscribed 6) Taboo 7) Unmentionable 8) Verboten 
• (a.) Not permissible.
Im`per·mis'si·ble adjective Not permissible. 
[adj] - not allowable 2. [adj] - not permitted
impermissible, impermissibility 1. Not permissible or allowable; unallowable. 2. Not permitted.
adjective not allowable
not permissible or allowable; unallowable.