Mostly used as a slang. Peoples from Quebec will use this a lot it especially "les racailles" kinda means wassup babygirl
I suggest running away if someone tell u this u don’t wanna become friends with them

n. The birth name of somebody who has changed their name. Most commonly attributed to trans people, but can be attributed to any person who has changed their name. (sometimes written as two words: dead name)

v. 1. To call somebody by their deadname.
v. 2. To out somebody's deadname to the public.