아리운 meaning, explanation

Question

The second part of the Alchemy of Souls OST is a song called 아리운 (Aching). While it is obvious to say that 아리운 means aching, I would like an explanation of what kind of word it is, as I can't seem to find anything similar in a dictionary.

My best guess would be that it is a combination of words like 그리움, 어려운, 아름다운... but it seems a little bit far fetched.

Here is the part of the lyrics where it appears and a link to the rest.

하얀 눈 위로 피어나는 꽃처럼
이 험한 길 위에 홀로 버텨온

찬란한 그대의
아름다운 이름

아리운 내 마음
깊은 곳에 새겨본다
새겨본다

Answer 1

아리운 is just a nonstandard form of 아린, which is an adjective form of 아리다 = to ache with a tingling sensation. 아리다 commonly used in phrases like 아린 느낌 = tingling sensation; 매운 걸 먹었더니 혀가 아리다 = My tongue tingles after eating hot food); 아이를 떠나보내면서 그녀는 마음이 너무 아렸다 = Her heart ached sharply as she sent the child off.

Unlike the -ㅂ다 adjectives 그립다, 어렵다, 아름답다 which take the -운 (그리운, 어려운, 아름다운) from through ㅂ-irregular conjugation (ㅂ drops and ㅜ is added), 아리다 doesn't become 아리운 since it has no bottom ㅂ that causes it. It should be 아린. But in songs and poems such a stretching out of words is often used for effect and other reasons. It could be that adding an additional syllable allowed more room for musical flourishes or it could be to rhyme it with the other lines. Other examples would be 거친 들판 becoming 거칠은 들판, 몹시 lengthening to 모옵시 and so on.