İlgi eki -ki
-ki is a tiny suffix that turns a place or a possessor into 'the one at / on / in / belonging to that place'. bende = 'on me' → bendeki = 'the one I have'. orada = 'there' → oradaki = 'the one over there'. masada = 'on the table' → masadaki kitap = 'the book on the table'. Unlike almost everything else in Turkish, -ki does NOT take vowel harmony — it's always -ki.
What -ki really does
It builds a relative-attributive: it takes a locative or genitive noun and turns it into a modifier. masa (table) → masada (on the table) → masadaki kitap (the book that's on the table). You can also use it pronominally: masadaki alone = 'the one on the table'. The suffix attaches to a noun that already carries case, never to a bare stem.
On locatives — place
-de / -da + -ki: evdeki (the one at home), arabadaki (the one in the car), bahçedeki (the one in the garden), buradaki (the one here), oradaki (the one there), şuradaki (the one over there). The same pattern works with time: akşamki film (tonight's film, lit. 'the film of the evening'), dünkü gazete (yesterday's paper — note: dün + kü with harmony, see below).
The two harmony exceptions
-ki is normally invariant, but two time words trigger an old harmony: dün → dünkü ('of yesterday'), bugün → bugünkü ('of today'). Optionally öbür gün → öbürkü. Everything else takes plain -ki: akşamki, sabahki, gelecekteki.
On genitives — possession
-(n)in + -ki = 'the one belonging to X'. benim (my) → benimki (mine). senin → seninki (yours). onun → onunki (his/hers). bizimki (ours), sizinki (yours pl.), onlarınki (theirs). 'Whose book is this?' — Bu benim kitabım, seninki nerede? = 'This is my book, where's yours?'
Stacking case after -ki
Once you've added -ki, the whole word can take more case endings, with a buffer n before them: masadaki + -ni (acc) → masadakini ('the one on the table' as object). bendeki + -ni → bendekini ver ('give me the one I have'). Plurals take n too: masadakiler = 'the ones on the table'.
