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1.
A terminally grumpy person, often genetic. Can be modified for various states of grumpitity.

Cheer up, don't be such a Grumpus!

That Grumpus has been growling at me for hours.

A Slumpus (A sleepy Grumpus)

A Lumpity Grumpus (A lumpier than average Grumpus)
by Dar123 January 02, 2009
 
2.
A girl; when she wakes up and she is grumpy.
She may punch you, or make rude remarks.
Generally the grumpus has blonde hair and green eyes, and pouts her lower lip when she is angry.
"Wow, she just woke up and hit me in the face, what a grumpus!"
by dominikagirl November 04, 2009
 
3.
Marijuana that makes you cranky and or angry at fellow smokers or stoner friends.
Man that buds grumpus, im swayze.
by kb and ldogg December 06, 2003
 
4.
Marijuana that makes you grumpy when your with your friends or fellow stoners
Maan that weed must be grumpus, everyone is bein so custy
by Ldogg and Kb December 07, 2003
 
5.
1. A feeling one gets after smelling a foul and repulsive odor.
2. A description of something butt-nasty.
1. Man, I shouldn't have eaten that mexican fish, I am feeling pretty grumpus.
2. Finding a crap load of diarrhea in the stall, very grumpus.
by Hansel February 10, 2004