Learn Croatian: Materinski jezik se ne zaboravlja. - One's mother tongue is not forgotten.

In Croatian, adding se to an active verb is a very common way to create a passive or impersonal sentence. While it literally looks like "The mother tongue does not forget itself," it actually means "One does not forget the mother tongue" or "The mother tongue is not forgotten."

Why do we use the imperfective verb zaboravlja instead of the perfective zaboravi?

The imperfective verb zaboravlja is used here because the sentence expresses a general, ongoing truth. It implies a continuous state where the language is never forgotten over time, rather than referring to a single, completed event of forgetting.

Could I say majčin jezik instead of materinski jezik to mean "mother tongue"?

Not naturally. Materinski is an adjective specifically meaning "maternal" or "native" in this context. If you used majčin (mother's), it would sound like you are referring to the specific language that your actual mother speaks, rather than using the fixed idiom for "mother tongue."

Why does the word se come before ne zaboravlja?

The word se is an enclitic, meaning it is an unstressed word that usually must go in the second position in a sentence. The noun phrase Materinski jezik acts as the first complete unit of information, so se naturally falls into the second position right after it.