User blog comment:ShalinP/Reforming English (written in current English)/@comment-30836812-20190316125757

From Middle English -s, -es, from Old English -as, nominative-accusative plural ending of masculine a-stem (i.e. strong) declension nouns, from Proto-Germanic *-ōs, *‑ōz, from Proto-Indo-European *-es, *-oes (plural endings).