You Do Need power plug adapter while traveling from Namibia to Ethiopia.

Here is Why You Need An Adapter

The outlet and plug type used in Ethiopia are C, F and G and in Namibia are D and M. This is how they look like.

Namibia

In Namibia, outlets of type D and M are in use.

Type D

Type M

Ethiopia

In Ethiopia, outlets of type C, F and G are in use.

Type C

Type F

Type G