WordNet records no synonym and no antonym for domestic terrorism. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
terrorism practiced in your own country against your own people
“the 1995 bombing of a federal building in Oklahoma City was an instance of domestic terrorism”
Synonyms, antonyms and the broader and narrower relations for domestic terrorism come from Princeton University’s WordNet. Full sources and licences.