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1.
a grumpy person. may or may express said grumpiness with non-human like grunts and sounds. definitely pouty and brooding.
An unexpected snowstorm in April turned Graham from a happy, human boy into a decidedly brooding grumpasaurus.
by Siducci April 17, 2007
 
2.
When someone gets tired and extremely grumpy
Why are you so grumpy right now?

"im tired"

no your being a grumpasaurus!
by tc61 April 22, 2011
 
3.
A dinosaur that is exceptionally grumpy, this term can be used to describe a woman when she is grumpy especially if she also looks like a dinosaur
guy#1- omg susie was in such a mood today.
guy#2- yeh and she is so fucking ugly
guy#1- what a grumpasaurus
by gapppo June 08, 2010