An extension of the common slang word bro. It's origin is unknown, but it has come to mean a bond of brotherhood exponentially stronger than bro. It is the deepest form of friendship, and the cloest two men can be without being homosexuals. In order to fully witness and realize the potential of so called 'brosivity', one must mix good friends with lots, and lots of beer.
Josh Salisbury, although he takes alot of shit, is a brosif.