Turkish Language - Some Rules about using Buffer Letters

Turkish makes use of three buffer letters -n- -y- -s- mainly to keep vowels apart when adding suffixes. There are rules on the choice of these suffixes which will be discussed below.

The buffer letter -S- (with the third person - "he, she it")

The -s- buffer letter is only used with the third person suffix -i, -ı, -u, -ü meaning his, her, its. The suffix -i -ı -ü -u - his, her, its - always takes buffer letter -s- thus taking the form -si -sı -sü -su when added to a root word which ends in a vowel.

The buffer letter -s- is only used for the third person singular possessive suffix - it is not used in any other instance.

The buffer letter -Y- (plain nouns only)

This is used ON PLAIN SIMPLE UNSUFFIXED NOUNS with the suffix -I - "the.. (objective)" - the Direct Object Condition (Accusative)

The suffix -i, -ı, -u, -ü - Direct Object Pointer - always takes buffer letter -y to become -yi, -yı, -yu, -yü - when added to a root word which ends in a vowel.
kedi - cat - becomes - kediyi - the cat (object)
banka - bank - becomes - bankayı - the bank (object)
To reiterate: - The buffer letter -y- is only used with simple nouns ending in a vowel which have not already been suffixed.
However it takes buffer letter -n- to become -ni, -nı, -nu, -nü when added as a second suffix to an already extended noun (as follows).

The buffer letter -N- (extended nouns only)

This is used on ALREADY SUFFIXED NOUNS with the suffix -I - "the.. (objective)" - the Direct Object Condition (Accusative)

Buffer letter -n- is onlly used with nouns that have already been suffixed.
kedisi - his/her cat - becomes - kedisini - his/her cat (object)
bankası - his/her bank - becomes - bankasını - his/her bank (object)
This shift of buffer letter - y to n - enables the listener to discern that the word is already agglutinated (extended) by previous suffixes.
To reiterate: - The buffer letter -n- is used on nouns which have already been extended by the addition of a suffix

The buffer letters -Y- and -N- (with -a/-e)

These are similarly used as the rules above with the suffix -a, -e - "to, towards.." - the Movement Toward Condition (Dative)

The suffix -a, -e - to, towards - always takes buffer letter -y to become -ya -ye - when added to a root word which ends in a vowel.
kedi - cat - becomes - kediye [kedi-y-e] - to the cat
banka - bank - becomes - bankaya [banka-y-a] - to the bank
baba - father - becomes - babaya [baba-y-a] - to the father
The buffer letter -Y- is only used with simple nouns which have not already been suffixed. But it takes buffer letter -n- to become -ne, -na when added as a second suffix to an already extended noun. This shift of buffer letter - y to n - enables the listener to discern that the word is already agglutinated (extended) by previous suffixes.

Buffer letter -n- is only used with nouns that have already been suffixed.
kedisi [kedi-s-i] - his/her cat - becomes - kedisine [kedi-s-i-n-e] - to his/her cat
bankası [banka-s-ı] - his/her bank - becomes - bankasına [banka-s-ı-n-a] - to his/her bank
babaları [baba-ları] - their father - becomes - babalarına [baba-ları-n-a] - to their father
To reiterate: The buffer letter -n- is used on nouns which have already been extended by the addition of a suffix.

The Buffer Letter -N- (with -da/-de and -dan/-den)

Is also used with -de -da - "in, on, at" - and -den -dan - "from, via, by, through", to keep the suffix apart from the noun it modifies.

The suffixes -de and -dan are added directly to basic nouns
kedi - cat becomes kedide [kedi-de] - on the cat
kediden [kediden] - from the cat
kapı - door becomes kapıda [kapı-da] - on/at the door
kapıdan [kapıdan] - from the door

They become -nda and -ndan when added to nouns which are already suffixed in order to keep the suffix apart from the extended noun:
kedisi - his cat becomes kedisinde [kedi-si-n-de] - on his cat
kedisinden [kedi-si-n-den] - from the cat
kapısı - door becomes kapısında [kapı-sı-n-da] - on/at the door
kapısından [kapı-sı-n-dan] - from the door

Some examples

Both the suffixes -de and -den require a buffer -n- when added to an extended word.