Fourth World also
fourth worldn.The least-developed countries of the Third World, especially those in Africa and Asia.
[TahlilGaran] American Dictionary ▲
fourth world n.,
informal The poor nations of the world, as distinguished from the oil-rich nations of the third world.
Sri Lanka will never join OPEC, since it is a fourth world nation. [TahlilGaran] English Idioms Dictionary ▲