The definition of poaching is simple. Though it may not be acceptable to all of us. An individual who commits the act of poaching knowingly or not knowingly would be considered a poacher for each individual act.
Both. What is the act of poaching by defintion? Is it simply breaking a game law?
Or are you trying to look the poaching as an adjective to describe or label an indivual. In that case are you asking how my acts of poaching, and/or how serious of an act (poaching) does one need to commit in order to be labeled a poacher?
I think the term poacher or poaching is thrown around much to liberally. Breaking a game law doesn't make someone a poacher anymore than speeding makes someone a criminal.