The term 'not allowed' can be expressed in a variety of ways, such as 'VERBOTEN' (8 letters), 'TABU' (4 letters), 'TABOO' (5 letters), 'ILLICIT' (7 letters), 'Ruledout' (8 letters), 'FORBIDDEN' (9 letters), 'CONTRABAND' (10 letters), and 'Againsttherules' (15 letters). These words all refer to something that is prohibited or not allowed by law, custom, or social convention. In general, these words are used to describe activities, objects, or behaviors that are considered unacceptable or off-limits.