A young, cool teacher that is easy to hang out with during school. (Commonly treated more as a peer than a teacher) It is found more times than not that teachers despise this name.
Comes from a combination of Bro and the first three letters of the word "sensei", which means teacher in Japanese.
"Yo Brosen, is there any assignment for tonight?"
"Hey Brosen, you wanna meet up after school and play some ball?"