"Unusual" here means "least similar to the name of any other country," with similarity measured by minimum edit distance. Name the countries with a minimum edit distance of 8 or more to their nearest match.
A brief explanation of "minimum edit distance" can be found in the instructions to this quiz.
"Nearest Match(es)" is not necessarily an exhaustive list.
"Dominica" and "Dominican Republic" obviously look and sound very similar to a human, but by minimum edit distance they are 9 steps apart (the fastest way to convert "Dominican Republic" to "Dominica" is to delete the final 9 letters).