i found this on Wiki aso it MUST be true lol
But it does match up with what guessed, it seems it means "sorrow"
http://www.uesp.net/wiki/Lore:Dragon_Language
http://elderscrolls.wikia.com/wiki/Krosis
"Krosis means 'no' in the dragon language."
I makes sense if you listen to Paarthunax talk and replace each instance of him saying "krosis" with "no."
There's a section labelled notes under the images. That's where I got my quote.on the link you have provided, the very 1st sentance on that page states:
"Krosis is one of 8 named Dragon Priests of Skyrim. His name means Sorrow in the Dragon Language. He is found at Shearpoint in the company of a dragon"