The conjunction Ki, which should not be confused with the pronominal suffix -ki, is one of the most tangled words in the Turkish language. I will go through it in this post. Its uses are;
1- Relative clause
Ki is the one and only subordinator in the Turkish language. Because Turkish has borrowed it from Persian-a language that shares a common origin with English, its use is the same as English "that". However, their meanings may occasionally differ.
Bir kimse ki söz dinlemez, ona ne söylesen boştur. = He is the kind of person that does not listen, it is futile whatever you say to him.
Babamız ki göktesin, adın kutsal kılınsın.* = Our Father who art in heaven, hallowed be thy name.
Bir de baktım ki kaçıp gitmiş. = And I saw that he had run away.
Canı sıkıldı, o denli ki dokunsan ağlayacak gibiydi. = She grew annoyed, so much so that she seemed as if she were about to cry.
A side note: Dokunsan ağlayacak olmak is an idiom meaning "to be about to cry", in a sense, you are so emotional that even if someone does an action as harmless as touching you, you will shed tears.
Sen ki benim en iyi arkadaşımdın. = You were my best friend.
2- So that
Patlıcanları ince ince doğra ki güzel pişsin. = Slice the eggplants small so that they will cook well.
Şöyle gel ki yüzünü göreyim. = Come here so that I will see your face.
İlaçlarını iç ki çabucak iyileş. = Take your medications so that you will get better soon.
Ara sıra öyküler yaz ki kalemin güçlensin. = Occasionally write stories so that your writing skills will become strong.
3- Stating the incompatibility of the situations described in given two sentences
This time, the second statement will be wrong as a result of the first.
Suçlu değilim ki çekineyim! = I am not guilty, so I am not embarrassed!
Sınav sonucum açıklanmadı ki notumu bileyim. = My exam result has not been announced, so I do not know my grade.
As you might notice, the first statement is a positive sentence when ki means so that, and the first statement is a negative sentence when ki means so...not.
4- Ending a response that expresses inability, impossibility, or a complaint as an intensifier
Ne demek bilmiyorum ki. = I do not really know what it means.
Gel desen de gelemem ki. = But I can not come even if you tell me to.
Peki diyorsun ama sana güvenilmez ki! = You are agreeing, but you can not be trusted!
5- Expressing worry in questions
Öyle desem alınır mı ki? = I am worrying, will he resent me if I tell him so?
Bu yarışmayı kazanabilecek misin ki? = I am worrying, will you be able to win this competition?
Common set phrases and words
Tabii ki (Of course)
Bugün tabii ki seninle geleceğim. = Today, of course, I will go with you.
Çünkü (Because)
Ben şimdi sizin fikrinizi tenkit etmeyeceğim çünkü faydasızdır.** = I will not criticize your opinion now because it is pointless.
Belki (Maybe)
Belki onu da göreceğiz. = Maybe we will see her too.
Sanki (As if)
Sanki tek suçlu benmişim gibi. = As if I am the only one to blame.
İyi ki (Gratefully, I am grateful that)
İyi ki varsın. = I am grateful that I have you.
Mademki (Seeing that)
Bakma sen, mademki tanıdıkmış bulur bir çaresini. = Don't worry, seeing that it's a friend, she'll find a solution.
Hâlbuki (However, in fact)
Hâlbuki ev sahibi tamirattan kaçınıyor. = However, in fact, the landlord avoids repair.
Oysaki (Whereas)
Gençler şiiri sevmiyor, oysaki şiir onların duygularını eğitir. = The youth does not like poetry, whereas poetry developes their emotions.
Meğerki (Unless)
Bu iş bitmeyecek meğerki siz de yardım edesiniz. = This will not be completed unless you, too, help.
Demek (oluyor) ki (Then)
Demek ki anlamadılar benim ne yaptığımı. = Then they did not understand what I did.
Şöyle ki (The thing of it is)
Şöyle ki, sadece tek şansımız var. = The thing is, we only have one shot.
Velev ki (Supposing that)
Velev ki pişman oldu ve özür diliyor, yine de onu affetmeyeceğim. = Even supposing that she is regretful and apologizes, I will not forgive her.
Tut ki (Supposing that)
Tut ki piyangoyu kazandın, o parayla ne yaparsın? = Supposing that you won the lottery, what would you do with the money?
*From the Lord's prayer, translated as Gerçek Dua into Turkish.
**From a quote of Ömer Seyfettin