i Register
In some senses, tomboy is marked as obsolete, colloquial. Watch for register when choosing this word.
noun
A girl who behaves in a typically boyish manner.
His sister, his dearest and only playmate, is a tomboy at heart.
“When you have a little girl like mine who is obsessed with the ocean and giant squids and insect infestations in homes, she’s considered weird or odd or a tomboy when in fact, science and things like that should be considered girly.”
A rude, boisterous boy.
An immodest or bold woman.
A butch lesbian.