= atom bomb, n. Also in extended use. Cf. hydrogen bomb n. at hydrogen, n. compounds 1a(b).

A bomb which derives its destructive power from the sudden release of a large amount of energy by fission of heavy atomic nuclei, causing damage…

A fission bomb. Now historical.

an atomic bomb in which uranium is the fissile material.

= atom bomb, n.

a bomb that derives its power from nuclear fission or fusion; an atom bomb or thermonuclear bomb.

a nuclear bomb whose explosive force is derived from the fission of plutonium.

Originally: a detonating mechanism for an explosive. In extended use: any explosive or incendiary apparatus; spec. a nuclear bomb (in full, and…

The fusion or hydrogen bomb.