Act of terrorism and Nuclear terrorism

Act of terrorism 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 act of terrorism are semantically related. In some cases you can replace phrase "Nuclear terrorism" with "Act of terrorism", this phrases are similar.

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.

Act of terrorism and nuclear terrorism are semantically related. You can use "Act of terrorism" instead a noun phrase "Nuclear terrorism".