Wikipedia
Potassium oxide
Potassium oxide ( K O) is an ionic compound of potassium and oxygen. This pale yellow solid, the simplest oxide of potassium, is a rarely encountered, highly reactive compound. Some materials of commerce, such as fertilizers and cements, are assayed assuming the percent composition that would be equivalent to KO.
Usage examples of "potassium oxide".
There are no freshwater fish on this world and the ocean fish have too high a concentration of potassium oxide in their flesh, for what cause I was not informed.