ki and -ki: Three Different Items

Turkish has not one ki but three, and they are spelled almost identically, which is exactly why learners (and spell-checkers) struggle. One is a separate word — the Persian-borrowed conjunction ki that introduces a clause. The other two are attached suffixes — the relativizing/possessive -ki (as in evdeki, benimki) and a temporal -ki (as in dünkü). The good news: spacing and a single quirky spelling rule sort all three apart cleanly. This page is the map; the conjunction itself is treated in depth on The Connector ki (Persian Borrowing).

ki #1: the conjunction ki (a separate word)

The conjunction ki is a free word, written with spaces, borrowed from Persian. It links a main clause to a following finite clause — roughly English "that," but it works left-to-right, the opposite of the native Turkish nominalized strategy. You state the main verb, then ki, then a complete tensed clause.

The defining marks of conjunction ki: it is a separate word, and the clause after it is fully finite (gelecek, unuttun, duramıyorum all carry tense and person). It also appears in fixed expressions like çünkü (çün + ki), belki ("maybe"), and hâlbuki ("whereas"), where it has fused into a single written word — but those you simply memorize. For the full range of clause types it introduces, see ki-Clauses: Finite Subordination.

ki #2: the relativizing/possessive suffix -ki (attached)

The suffix -ki attaches to a noun phrase — typically one already marked locative or genitive — and turns it into a new noun phrase meaning "the one that is (at/in) X" or "the one belonging to X." It is attached (no space) and it has a famous oddity: it does not obey vowel harmony. It stays -ki regardless of the preceding vowel, where harmony would predict -kı / -ku / -kü. So it's evdeki, never evdekı.

On a locative base it means "the one at / in …":

On a genitive base it means "the one belonging to …" — this is how Turkish says "mine, yours, ours" as standalone pronouns:

In masada-ki, bahçede-ki, benim-ki, bizim-ki, the suffix is glued on and invariant. That invariance is the giveaway: a harmonizing suffix would adjust its vowel; -ki refuses to. (When a noun follows this suffix and gets case-marked, a buffer -n- appears — evdekinde — which is the same buffer logic explained on Buffer Consonants y, n and s.)

ki #3: the temporal -ki (with a harmonizing exception)

A small set of time words take the same attached -ki to mean "the one of / belonging to [that time]." Here — and essentially only here — the suffix does bend to harmony in a couple of high-frequency words, giving the rounded form -kü: dün → dünkü ("yesterday's"), bugün → bugünkü ("today's"). Most other time words keep the plain -ki: yarın → yarınki, akşam → akşamki, sabah → sabahki.

So dünkü and bugünkü round to -kü after their ü/ü vowels, while yarınki keeps plain -ki despite the back vowels in yarın. These rounded forms are the only routine exceptions to the "-ki never harmonizes" rule; treat them as memorized items.

The three side by side

The deciding questions, in order: Is it a separate word introducing a tensed clause? → conjunction. Is it glued to a noun and unchanging? → suffix -ki. Is the host a time word and does it sometimes round to -kü? → temporal -ki. Spacing tells the conjunction from the suffixes; the host (clause vs noun vs time word) tells the two suffixes apart. Note that this -ki has nothing to do with the additive de/da clitic, which is a separate word with its own spelling rules.

Common mistakes

Spacing the suffix off is the most common error, because the conjunction ki is a separate word and learners overgeneralize. The relative/possessive -ki is glued on: masadaki, benimki.

Vowel harmony tempts you to write -kı after the back vowels of bahçede, but -ki refuses to harmonize. It stays -ki.

The reverse error: gluing the conjunction on. Because it introduces a finite clause, ki here is a free word and needs its space.

dünkü and bugünkü are the rare rounded exceptions; writing dünki misses the one place where this suffix does round.

Key takeaways

• Conjunction ki is a separate word introducing a finite clause: Biliyorum ki…, Sandım ki….
• Suffix -ki (relative/possessive) is attached and invariant — never harmonizes: masadaki, benimki, bizimki.
• Temporal -ki attaches to time words and keeps -ki (yarınki, akşamki) except for the rounded dünkü and bugünkü.
• Spacing separates the conjunction from the suffixes; the host (clause vs noun vs time word) separates the two suffixes.
• Never harmonize -ki to -kı (apart from dünkü/bugünkü), and never glue the conjunction ki.