Where does “*krīskan” come from?

*krīskan (Proto-West Germanic) comes from Proto-Germanic krīskaną, from Proto-Indo-European grey- — to shout.

Ancestry of “*krīskan”, step by step

Step	Language	Word	Meaning
1	Proto-Germanic	krīskaną	to scream, shout, screech
2	Proto-Indo-European	grey-	to shout

*krīskan — Etymology, Origin & Word History | Etymology Explorer