From Old Armenian -ք (-kʿ). The -եք (-ekʿ) in երեխեք (erexekʿ) and other words ending in -ա (-a) developed from Old Armenian -այք (-aykʿ), through the regular sound change այ (ay) → ե (e); thus Old Armenian երեխայք (erexaykʿ) → Armenian երեխեք (erexekʿ).
-ք • (-kʿ)
- (colloquial, dialectal) plural nominative case marker for words suffixed with -ցի (-cʿi) and certain others
- Jasmine Dum-Tragut (2009), Armenian: Modern Eastern Armenian, Amsterdam, Philadelphia: John Benjamins Publishing Company, page 65, ISBN 9789027238146
The origin is uncertain. What follows is Matasović’s summary of opinions.
Some scholars (e.g. Meillet and Godel) take the obvious course and derive it from Proto-Indo-European masuline-feminine plural nominative case ending *-s, but the sound development of word final *-s to *-ք (*-kʿ) is not universally accepted. Other linguists assume a pronominal particle added to the bare stem, but the origin of that particle has never been explained. A recent hypothesis derives -ք (-kʿ) from the agglutinated Proto-Indo-European *dwóh₁ (“two”); it would have been originally a dual marker, subsequently replacing the inherited plural. Another possibility, which is a mere speculation: the plural marker -ք (-kʿ) can be regularly derived from *-s-wes, with the ending of the u-stems *-w-es agglutinated to the regular nominative plural marker *-s.
-ք • (-kʿ)
- plural nominative case marker
- forming names of countries
- Armenian: -ք (-kʿ)
- Robert Godel (1975), An introduction to the study of classical Armenian, Wiesbaden: Dr Ludwig Reichert Verlag, page 102
- Ranko Matasović (2009), A Grammatical Sketch of Classical Armenian, Zagreb, page 19