Gender adjectives in Scribblenauts are adjectives used to give people and things gendered (male or female) characteristics.
Super and Remix
It make things act like males or females. Symbols of the respective adjectives appear as speech bubbles above their heads.
The things with the male adjective will be attracted to the things with the female adjective and vice-versa.
It replaces the sprite and makes it a male or female. For example, pirates usually appear as males, but if you apply the female adjective on a pirate, it will appear as a female instead. Some characters such as a geisha and a flower girl only come in one gender.
In Unlimited and Unmasked, you can type in "female man" and "male woman". These will give you a woman and a man respectively.