Where does “-ок” come from?

-ок (Russian) comes from Proto-Slavic -ъkъ, from Proto-Slavic -kъ, from Proto-Indo-European -kos — Creates deadjectival and desubstantival...

Ancestry of “-ок”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	-ъkъ	Forms diminutives from old u-stem nouns;...
2	Proto-Slavic	-kъ	Deverbal, forms token nouns; From expressive or...
3	Proto-Indo-European	-kos	Creates deadjectival and desubstantival...

-ок — Etymology, Origin & Word History | Etymology Explorer