WordNet records no synonym and no antonym for foreign direct investment. It is the only member of each of its synsets, 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.
investing in United States businesses by foreign citizens (often involves stock ownership of the business)
a joint venture between a foreign company and a United States company
Synonyms, antonyms and the broader and narrower relations for foreign direct investment come from Princeton University’s WordNet. Full sources and licences.