Learn Turkish: Biz on yıldır çocukluk arkadaşıyız. - We have been childhood friends for ten years.

çocuk means "child." The -lIk suffix is used to create abstract nouns from other nouns or adjectives. Following vowel harmony rules, the suffix becomes -luk here, transforming "child" into "childhood" (çocukluk).

Why is it çocukluk arkadaşı and not just çocukluk arkadaş?

This is a classic Turkish noun compound. When you pair two distinct nouns together to name a specific concept—like "childhood" (çocukluk) and "friend" (arkadaş)—Turkish requires a compound marker on the second word. That's why arkadaş gets the -ı suffix.

Can you break down the very end of arkadaşıyız?

Sure! It starts with the noun compound çocukluk arkadaşı (childhood friend). To say "we are childhood friends," we must add the "we" personal ending, which is -ız. Because arkadaşı already ends in a vowel, we have to insert the buffer letter -y- to connect them smoothly, resulting in arkadaş-ı-y-ız.

What does the -dır suffix do in on yıldır?

When attached to a time expression like on yıl (ten years), the -dır suffix functions like the English word "for." It indicates that a situation started in the past, has been going on for that amount of time, and is still continuing right now.