-구나

First attested in the Beonyeok baktongsa (飜譯朴通事 / 번역박통사), before 1517, as Middle Korean -고〮나〮 (Yale: -kwóná).

구나 • (-guna)

1. a plain-style exclamatory suffix used to express a certain feeling (surprise, wonder, admiration, etc.) upon discovering or hearing about a new fact.

   제주어는 참 배우기 힘든 언어구나.

   Jejueo-neun cham bae'u-gi himdeun eoneo-guna.

   Wow, the Jeju language is a really difficult language to learn.

   이 노래도 아는구나!

   I norae-do a-neun-guna!

   You know this song too!

   이 그림은 정말 아름답구나.

   I geurim-eun jeongmal areumdap-guna.

   Wow, this painting is so beautiful.

   그 분이 돌아가셨구나.

   Geu bun-i doragasyeot-guna.

   So he has passed away.

   자네도 곧 떠나겠구나.

   Jane-do got tteona-get-guna.

   So you will be leaving soon, too.

• For verbs, the bare form cannot be used; it must be marked with tense/aspect, i.e. 는 (-neun-, present-tense suffix), 더 (-deo-, retrospective suffix), 었 (-eot-, past-tense suffix), 겠 (-get-, future-tense suffix). This is not the case for adjectives.