Learn Turkish: Şeytanın ne demek olduğunu sordu.

In direct speech, "What does the devil mean?" is Şeytan ne demek? To make this an indirect question, we need the factive suffix -dIğI. Because ne demek acts as a fixed phrase here, we use the helper verb olmak (to be) to attach the suffix, creating ne demek olduğu.

Why is "devil" written as Şeytanın with the genitive suffix instead of just Şeytan?

In a Turkish embedded clause created with -dIğI, the subject of that clause must take the genitive case. Since "the devil" is the subject of the phrase "what the devil means", Şeytan takes the genitive suffix -ın.

Let's break down olduğunu. Why are there two -u suffixes at the end?

The word breaks down as ol-duğ-u-n-u. The first -u is the 3rd-person possessive suffix, which completes the genitive-possessive pair with Şeytanın (literally, "the devil's being"). The -n- is a buffer letter. The final -u is the accusative case marker, used because the entire embedded clause is the direct object of the verb sordu (he asked).

Why does demek translate to "means" instead of "says"?