친구 (chin-gu) friend is the standard everyday word for a friend.
절친 (jeol-chin) best friend is the common short form for a very close friend.
친한 친구 (chin-han chin-gu) means close friend.
친구 (chin-gu) means "friend" – a person you know well and like.
1. Talking about friends: "친구 만나러 가? (chin-gu man-na-reo ga?)" (Going to meet friends?).
2. Closest person: Using 절친 (jeol-chin) best friend.
3. Comfortable relationship: Saying 친한 친구 (chin-han chin-gu) close friend.
Going to meet friends?
It's my best friend's birthday.
I'm meeting my close friend.
• 절친 (jeol-chin) best friend
• 친한 친구 (chin-han chin-gu) close friend
• 오랜 친구 (o-raen chin-gu) long-time friend