My definition is someone who gets high on a daily base, enjoys its, and only sticks to pot.
Ren: nothing got high.
Mel: What else do you have planned.
Ren: ugh maybe get high again.
Mel: Whhat.... Ren your just a pot head.
Ren: SO I LOVE IT HAHA
Lives and breathes the GANJA!
Don't get it confused with a stoner, stoner's smoke in moderation.