Nuclear weapon and Thermonuclear bomb

Nuclear weapon noun - A weapon of mass destruction whose explosive power derives from a nuclear reaction.

Thermonuclear bomb and nuclear weapon are semantically related In some cases you can use "Thermonuclear bomb" instead a noun phrase "Nuclear weapon".

Thermonuclear bomb noun - A nuclear weapon that releases atomic energy by union of light (hydrogen) nuclei at high temperatures to form helium.

Nuclear weapon and thermonuclear bomb are semantically related in nuclear bomb topic. You can use "Nuclear weapon" instead a noun phrase "Thermonuclear bomb", if it concerns topics such as atomic bomb.