These words all mean to break out, open or apart in a sudden and violent way, as if from some internal force. Explode has specific reference to the physical phenomenon which occurs when any substance or mixture of substances react on impact or by ignition with a sudden expansion of gases and the liberation of relatively large amounts of thermal energy. Explode , in this sense of blowing up, suggests more violence and noise than any of the other words in this group.

• The bomb exploded at a great distance from our observation point but with so much noise that I was deafened for several minutes.

The same kind of noisy breaking out is implied when explode is used figuratively to indicate the sudden release of an emotion: to explode with laughter; to explode with anger. Another figurative usage of explode is its designation of the destruction of something by disproving, refuting or discrediting it: to explode an out-of-date theory; a tissue of lies that was exploded by an honest slip of the tongue. Burst , like explode , can mean to blow up: the sound of shells bursting over our heads. It has, however, more general applications than explode in the sense of breaking out or apart. Here, in a literal or figurative way, it suggests the energy produced by a sudden release from confinement or the force generated by great tension: a dam that burst during a season of heavy floods; the feeling that one is about to burst from overeating; to die as a result of a blood vessel that burst in the brain. Burst is also used figuratively like explode to denote the expressing of an emotion: a man who was bursting with resentment.

Erupt , which is also used literally and figuratively, means to burst forth or to break out. In this word, as in the one sense of burst , there is an implication that the bursting or breaking out is done from a restrictive place or condition.

• Hot ashes and molten lava erupted from the volcano; angry oaths suddenly erupted from the man who had been fighting to keep his temper under control.

Bust , in the sense pertinent to this comparison, means to break open or apart. It is a slang variant of burst : a couple of drunken guests who in seconds busted all the balloons it had taken me hours to blow up.