WordNet records no synonym and no antonym for lost tribes. 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.
the ten Tribes of Israel that were deported into captivity in Assyria around 720 BC (leaving only the tribes of Judah and Benjamin)
Synonyms, antonyms and the broader and narrower relations for lost tribes come from Princeton University’s WordNet. Full sources and licences.