The human equivalent to super sayjin. said person who is in beast mode is stronger can jump higher run faster and fight harder for longer.
definition 2. the more evolved form of the primitive emotion of rage or bodily chemical (adrenaline)
DUDE! CASEY AND SPENCER GOT IN A FIGHT, CASEY WENT BEAST MODE AND SLAMMED SPENCER THROUGH THAT OAK DESK!!
original origin- from beast wars. where mechanical aliens switched into their animal counterparts to heal wounds or fight with primal fury.