Top definition
Gray stuff that is often found in the bottom of cups or bowls. It is believed that Koostis was originally created by mount koostis which burn to ashes after shooting out millions of gallons of koostis from it's peak.

Koostis is also often refered to as anything you want it to be
Calm your Koostis
by THat annoying koose January 25, 2011
Happy St. Patties Day!
buy the domain for your diy site