belle means beautiful so the opposite is: ugly
"Belle" (fem.), meas beautiful. The opposite is "laide" (fem.) meaning "ugly".
beau
Opposite gender=male
Belle
belle
The male counterpart of "belle" is "beau".
Doctor is a neuter gender
The feminine of old beau could be "an old belle" but this does not have exactly the same connotation as beau (boyfriend or suitor). The derivative slang term "boo" can be used for either gender.
Belle
Clot is not gender specific.
An emperor is the opposite in gender to an empress.
Opposite gender of Filipino: Filipina
The opposite gender of fraternity is sorority.
The opposite gender of giantess is giant.