Some roots in Turkish lose their final vowel when a vowel-initial attaches to them. Here’s a list of some common roots, inflected with the first person possessive suffix to demonstrate the phenomenon.
Let us call them ‘kaypak ünlü kelimeleri’, words with floating or ‘unreliable’ vowels.
Note that these words are either Arabic loanwords or nouns for body parts which are all Turkic originally.