Green being a well known "secret word" for cannabis, and fiend referring to someone who loves a certain substance, which is usually a drug. Similar to a dope fiend but with cannabis, it is someone who enjoys and loves cannabis so much that they'd consider themself just CRAZY about it in every which way, shape and form. They love the smell of it, the taste of it, to learn about it, etc. but most importantly the effects from it.
Wow Mike you are always smoking tree, learning about it on Leafly, and looking for a good delivery service on Weedmaps; you are such a green fiend! You're almost as crazy about weed as I am, but that's why you're my best bud!
by ArcTheShark21 March 09, 2015
A name commonly used to describe the type of person who likes to sit around all day chuffing on a fat marijuana bifter.
'That Robbie is a right green fiend, all he does is sit there smoking reefers and playing that bloody playstation all day'
by gogggg February 06, 2006