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.
The opposite gender of a beau is belle. A beau is a male admirer, while a belle is a female admirer.
belle
The male counterpart of "belle" is "beau".
Belle is typically a female name, often associated with the character from Disney's "Beauty and the Beast." The opposite gender would be "Beau," which is a male name and means "handsome" in French.
belle means beautiful so the opposite is: ugly
A swain is male admirer, a beau, a boyfriend; a female is a female admirer, a girl, a girlfriend, or leman, a word for sweetheart, lover, or mistress, as old fashioned as swain.
MALE
A swain is male admirer, a beau, a boyfriend; a female is a female admirer, a girl, a girlfriend, or leman, a word for sweetheart, lover, or mistress; a word as old fashioned as swain.
Belle
Doctor is a neuter gender
Opposite gender of Filipino: Filipina
Clot is not gender specific.