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# A more or less rounded mass of lava from a few inches to several feet in diameter, generally vesicular, at least inside, thrown from the throat of a volcano during an explosive eruption. 
# An ellipsoidal, discoidal, or irregularly rounded mass of lava ejected at a high temperature during a volcanic eruption. Bombs range upwards in size from the largest lapilli. They are characterized by a well-defined crust and are often cellular or even hollow internally. <I>Holmes, 2 </I>
# A missile containing an explosive, as dynamite. 
# A heavy-walled reaction vessel or autoclave. Used to carry out reactions at high pressure and high temperature. <I>Hurlbut </I>

Source: Dictionary of Mining, Mineral, and Related Terms