i kinda forgot what kanka means...  what is "kanka"?

something like "bro", i guess..

"kanka" comes from "Kan kardeþi" which means blood brother

well what is the word used for brother in law?

eniþte?

In daily usage, "kanka" means the same as "buddy". 

Example:

Naber kanka? = What´s up buddy?

"brother-in-law" means both "kayýn" and "kayýnbirader".

It stands for "the brother of one´s spouse". 

There is also another informal and intimate word which is "kayýnço" and

you can use it to address your brother-in-law while speaking to him as well as to name the relationship between you.

Example:

Naber kayýnço?

Your "eniþte" is your sister´s or aunt´s husband.

You can use "eniþte" to addres him while speaking to him.

Your "bacanak" is the husband of your wife´s sister. So unlike "kayýnbirader" and "eniþte", only men can have a "bacanak". You can use "bacanak" to address him while speaking to him.

I am adding this note because sometimes you may not address the person with the name which is acceptable to use when describing your relationship.

A good example of this is kaynana which means "mother-in-law",

but you should not use this word when you are speaking to her.

It is considered to be rude and most of Turkish people prefer saying "mum" instead.

Kaynana has a kind of negative connotation so most of the people use "kayýnvalide" even when describing their relationship with their mother-in-law.

To sum up, brother-in-law means "kayýnbirader", "eniþte" and "bacanak" at the same time.

But these three words have totally different meanings.