Nuclear terrorism and Terrorist act

Nuclear terrorism noun - The use of a nuclear device by a terrorist organization to cause massive devastation or the use (or threat of use) of fissionable radioactive materials.

Terrorist act and nuclear terrorism are semantically related. In some cases you can use "Terrorist act" instead a noun phrase "Nuclear terrorism".

Terrorist act noun - The calculated use of violence (or the threat of violence) against civilians in order to attain goals that are political or religious or ideological in nature; this is done through intimidation or coercion or instilling fear.

Nuclear terrorism and terrorist act are semantically related. Sometimes you can replace phrase "Nuclear terrorism" with "Terrorist act", this phrases are similar.