This is the 19312th most frequent Korean word.
알던
"알던" is the modifier form of the verb "알다," meaning "knew" or "used to know."
알던 is used to describe the person 'I used to know', implying familiarity or understanding in the past.
내가 알던 그 사람이 지금은 전혀 달라졌어.
The person I used to know has completely changed now.
알던 refers to a store that 'we used to know', emphasizing past familiarity or association.
우리가 알던 가게가 문을 닫았다고 들어서 아쉽네요.
I heard the store we used to frequent has closed; it's unfortunate.
알던 here compares the knowledge 'we used to know' in the past with the subject's wider knowledge.