There are two reasons why Siamese cats are called Siamese. Originally, Siamese cats come from Thailand. That is the country of their origin and before 1932 Thailand was called Siam.
The second reason is that the suffix ‘-ese’ means “belonging to” or “originating in”. This comes from old French and Latin.
So the word “Siamese” means originating in Siam which now means originating in Thailand. That’s an accurate description because, as mentioned, Siamese cats originate in Thailand. So the word ‘Siamese’ is a description of this cat breed.
That is the reason why Siamese cats are called Siamese. I hope this helps. There’s nothing more to say.