The noun adult is a common gender noun, a word for a male or a female.
Since a bull is referring to an adult or mature intact male, then, since the opposite of a male is female, the opposite of a bull would be a cow, which is an adult or mature female bovine that has had at least one or two calves.
Some people use "duck" specifically for adult females and "drake" for adult males, others use "hen" and "drake", respectively.
Doctor is a neuter gender
Opposite gender of Filipino: Filipina
Clot is not gender specific.
Opposite gender of a Filipino: FILIPINA
The opposite gender of farmer is farmeress or farmwife.
The opposite gender of fraternity is sorority.
The opposite gender for Joseph is Josephine.
The opposite gender of giantess is giant.
An emperor is the opposite in gender to an empress.
The opposite of dairymaid is dairyman.