Basically, someone who hasn’t quite realized they’re not entirely cis yet. “I thought everyone had dreams of being a boy/girl.” “I don’t get all that upset when I’m mistaken for a guy/girl on the phone.” “I don’t really feel comfortable hanging out with other guys/girls. It feels boring.”

Stuff like that. Other trans people can (usually) spot an egg a mile away. But like everything else in queerness, it’s never cut-and-dry, black-and-white, easily defined. They could always just be comfortable enough in their birth-assigned gender to not give a shit, and that’s valid.

It’s considered rude to assign this trait to someone you know personally, and the topic is only broached if the person in question chooses to be vulnerable and ask you specific questions about gender. Otherwise, they are (as always) your friend first, and treating them with care and respect always comes first.