The term 'prohibited practice' refers to an action or behavior that is not allowed or is forbidden. The two crossword solutions for this term are 'TABU' and 'nono'. TABU is a word of Polynesian origin which means something that is forbidden or sacred. Nono is a word derived from Spanish which means 'NO' or 'not allowed'. Both words refer to the same concept, that of something being prohibited or forbidden.