1. an act, action, or practice that is contrary to or forbidden by law; something illegal
The court ruled that the company's practices constituted an illegality.
O tribunal determinou que as práticas da empresa constituíam uma ilegalidade.
2. the quality or state of being illegal or unlawful
The attorney pointed out the illegality of the search without a warrant.
O advogado apontou a ilegalidade da revista sem mandado.