Where does “երեքին” come from?

երեքին (Old Armenian) comes from Old Armenian -եքին, from Proto-Indo-European -ēs, from Proto-Indo-European -ess, from Proto-Indo-European -os — Creates action nouns or result nouns from verbs;...

երեքին (Old Armenian): all three

Definitions

all three

Ancestry of “երեքին”, step by step

Step	Language	Word	Meaning
1	Old Armenian	-եքին	forming collective numerals
2	Proto-Indo-European	-ēs	Primarily forms adjectival bahuvrīhi compounds
3	Proto-Indo-European	-ess	—
4	Proto-Indo-European	-os	Creates action nouns or result nouns from verbs;...

Every word from Proto-Indo-European -os →Every word from Old Armenian -եքին →Every word from Proto-Indo-European -ēs →