[stevewilhelm]

Economists and 'social entrepreneurs' prefer the term developing world or developing countries in contrast to developed countries.

Countries can be evaluated using the Human Development Index to determine their designation.

[sandworm101]

>> developing world or developing countries

Those terms denies the possibility that such conditions may be present in developed countries, which was the point of the above criticisms.

[timlyo]

Less economically developed country is another term that is commonly used.