-iyor

• -iyo (informal)
• -iy, -iyi (dialectal, rustic)
• -io (text messaging)
• -iyoru (dialectal, Eskişehir)
• -iye (dialectal)

Inherited from Ottoman Turkish ـییور (-iyor, -ıyor), from Old Anatolian Turkish ـه‌یورر (-eyorur, -ayorur), ـه‌یور (-eyor, -ayor), from Old Anatolian Turkish یورمق (yorımaq), یورمك (yörimek), from Proto-Turkic *yorï- (“to walk”), which was used as an auxillary verb. Cognate with Gagauz -er, -êr, Azerbaijani -ir, -ır, -ür, -ur, Turkmen -ýär, -ýar.

-iyor

1. Suffix creating present continious tense, denoting action happening at the time.

   Niçin böyle düşünüyorsun? ― Why are you thinking so?

• The r in the suffix is often dropped in spoken language

  İçiyom (I am drinking) instead of içiyorum

  İçiyosun/İçiyon (you are drinking) instead of İçiyorsun

• Usual negative suffix -ma/-me turns into -mı/-mi/-mu/-mü when used with the present tense.

  Bakmıyorum (I am not looking)