Suppose Congress passes a bill and the President does nothin…

Suppose Congress passes a bill and the President does nothing with it. He/she just leaves it on the White House desk without signing it or vetoing it.  Usually, it becomes law after 10 days.  But, suppose Congress passed the bill when there are fewer than 10 days left in their session.   In this situation, when the session of Congress ends, the bill is dead. This is known as what?