When someone says “Be punctual,” that means you better be there on time. Five minutes late won’t cut it.
Some people seem to follow an appointment clock instinctively. We call those types punctual. They'll check their watch when you arrive three minutes late. The word punctual originates from the Latin word punctualis, which means “a point.” To be punctual, you have to arrive at the right point in time. For your appointment. Get the point?