A formal verb meaning to go past a line you were not supposed to cross — to break a rule, a law, or an unwritten social or moral standard. The picture underneath is physical: stepping over a boundary. That is why it feels bigger than 'break a rule'. You can transgress a law, but the word is at home with moral and religious wrong ('transgress God's commandments') and with the quiet rules nobody writes down ('he had transgressed by asking her salary'). It works with an object ('transgress the law') and without one ('those who transgress will be punished'). Register: high. In ordinary speech people say 'break the rules', 'go too far', 'cross the line' — you would sound odd saying 'I transgressed' about being ten minutes late. Two places you will actually meet it: religious and legal texts, where it is heavy and serious; and art, literature, and cultural criticism, where it has flipped positive — a 'transgressive' film or novel is one that breaks taboos on purpose, and critics often mean that as praise. So the same word can condemn or admire, depending on who is holding it.