1. A place where everybody belongs to a clique (because everyone has labels, like the plants in an arboretum). Sometimes shortened to arb.
2. Used to describe when simple-minded people n00bs move online acronyms over into real life, labelling their emotions with acronyms.
1. "Mike's not a jock, he's not a bad guy, this ain't an arboretum"

2.'Tard: "Ell Oh Ell"
Me:"Hey Dipshit, this is not a fucking arboretum."
by crazygoatemonky January 9, 2006
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1) A botanical garden living in someone's asshole
2) Someone who enjoys woody objects shoved in to their rectum
"When I fart, it smells like lilac"
"That's because you have a fucking flower garden in you anal arboretum"
by Nutzen YerMouf February 9, 2018
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