On Medial Vowel Loss or why 'oğul' becomes 'oğlum' and other similar cases

Medial Vowel Loss describes the phenomenon when a vowel is lost from some Turkish root/nouns when another suffix is added to it - as in the change from oğul (son) to oğlum (my son) - otherwise expected to become 'oğulum' following the general convention of the possessive suffix for the first person plural (-Im). Instead, the vowel in the middle (u) is lost and my son is 'oğlum' in Turkish. We provide a list of such cases.

Being an agglutinative language, learners of Turkish will rarely come across "exceptions" to grammar rules - which is why most people consider it a "mathematical" or "logical" language. However, there are some occurences of grammar points that may be percieved as "exceptions" to general rules. Medial Vowel Loss is the name to one such phenomenon; specifically it describes when some roots in Turkish lose their final vowel when a vowel-initial suffix attaches to them. Here’s a list of some common roots, inflected with the first person possessive suffix to demonstrate the phenomenon.

Note that the majority of these words are Arabic loanwords or body parts of Turkic origin.

ağız (mouth)
- ağzım (my mouth)
burun (nose)
- burnum (my nose)
karın (stomach)
- karnım (my stomach)
oğul (son)
- oğlum (my son)
şehir (city)
- şehrim (my city)
isim (name)
- ismim (my name)
kısım (part)
- kısmım (my part)
akıl (mind)
- aklım (my mind)
alın (forehead)
- alnım (my forehead)
beyin (brain)
- beynim (my brain)
boyun (neck)
- boynum (my neck)
devir (period, era)
- devrim (my era)
fikir (idea)
- fikrim (my idea)
hayır (benefit)
- hayrım (my benefit)
göğüs (chest)
- göğsüm (my chest)
gönül (heart)
- gönlüm (my heart)
nesil (generation)
- neslim (my generation)
ömür (life)
- ömrüm (my life)
resim (picture)
- resmim (my picture)
sabır (patience)
- sabrım (my patience)
şekil (shape)
- şeklim (my shape)
vakit (time)
- vaktim (my time)
zihin (intellect)
- zihnim (my intellect)