反义词是undeveloped，中文意思是adj. 未开发的不发达的未充分发育的
There are many people whose cultures are undeveloped， but the languages they speak are by no means primitive.有许多人他们的文化不发达，但他们说的语言绝不是原始的。
The big losers will be the undeveloped countries， especially in sub-Saharan Africa.
