Overdue means late, past the time when something was supposed to happen or be returned. When a library book is overdue, you've kept it longer than the library allows, and you might owe a fine. When homework is overdue, you've missed the deadline your teacher set.

The word carries a sense that time has run out. A bill becomes overdue when you haven't paid it by the due date. A baby is overdue when it hasn't been born yet, even though the expected delivery date has passed. A train is overdue when it should have arrived already but still hasn't pulled into the station.

People also use overdue to describe something that should have happened long ago. If your room is a complete mess, your parents might say it's overdue for a cleaning. When friends finally make up after a long argument, you might say their reconciliation was long overdue. A student who has worked incredibly hard all year but never gotten recognized might be overdue for some praise.

The word suggests not just lateness, but that the delay has gone on too long. Something overdue needs attention now.