To cause to burst forth; to eject; as, to erupt lava.
To eject something, esp. lava, water, etc., as a volcano or geyser; as, when Mount Saint Helens erupted, some people were taken by surprise.
To burst forth; to break out, as ashes from a volcano, teeth through the gums, etc.; as, the third molar erupts late in most people, and in some persons does not occur at all.