From Wiktionary, the free dictionary
Probably from Proto-Turkic *er-ser, doublet of ایسه (ise).
یسر • (-iser, -yiser)
- a verbal suffix added to the root-word of any verb, forming a future active participle
14th ce., Hoca Mesud, Süheyl ü Nevbahar:کوررلر ایرلو اویرلو بر آت ددیلر کلوسر ایشمز اوڭات- Gördiler eyerlü uyarlı bir at - Didiler geliser işümüz oŋat
- They saw a horse with a saddle and a halter and said, "We will be successful."