overpopulated
Namibia is the second least-populous country in the world, so you can say it is underpopulated.
I would say Nigeria is overpopulated. It is above the world average population density (world: 47/km2, Nigeria: 167/km2)
Nigeria is at under population, because her available resources exceed the population of it poeple!
Mexico as a whole is overpopulated but Mexico City has about 22 million people living there and it has been overpopulated for about 20-30 years.
Overpopulated
yes
No, they are underpopulated.
no
Yes
yes
With a population of 2.8 million people, most people would say Jamaica is not particulary overpopulated.