Learn Turkish: Nihai kararımız, bu projeyi ertelemektir. - Our final decision is to postpone this project.

This is an example of an infinitival predicate, which is the focus of this lesson. The -tir suffix acts as the copula (the "to be" verb), translating to the "is" in "Our decision is to postpone...". While you might hear it dropped in casual speech, adding -DIr to an infinitive is the standard way to state formal decisions or facts.

If the main "verb" of the sentence is just the -tir copula, why is proje in the accusative case (projeyi)?

Even though ertelemek acts as a noun (the predicate) for the entire sentence, it is still a verb at heart and governs its own objects. Because "this project" is the specific, defined object of the action "to postpone", it requires the definite accusative suffix -(y)i.

Could I say son kararımız instead of nihai kararımız?

Absolutely, son kararımız is very common and means the same thing. Nihai is an Arabic loanword that carries a more formal, official, or definitive tone (like "ultimate"). It pairs perfectly with the formal, factual tone created by the -tir suffix at the end of the sentence.

What is the purpose of the comma after kararımız?

In formal Turkish, a comma is frequently placed right after the subject to clarify the sentence structure. It visually separates the subject (Nihai kararımız) from the predicate phrase, making the sentence easier to parse at a glance.