사자성어 vs. 고사성어 vs. 한자성어
What are 4 character idioms?
When you watch Korean newspapers, or TV shows, you can see some strange words with 4 characters like 유비무환, 일취월장, etc. These words are called 사자성어, or 고사성어. 4 character idiom is the translation of 사자성어.
Many of them came from the old books and stories in Korea and China. Because of that, they are all made from Chinese Characters.
사자성어, 고사성어, 한자성어
These words are called in 3 ways, 사자성어, 고사성어, 한자성어. They are fairly interchangeable, but there are some differences.
To understand the differences, you should understand the definition of each word.
사자(四字) in 사자성어 means 4 letters. It is not a lion. 성어 means a word or idiom. 사자성어 means 4 letter words. The phrase, 4 letter words, seem clear and innocent to some of you. However, it is not to others. Unfortunately, 4 letter words mean swear words. Because of that, I use 4 character idioms than 4 letter words.
고사(故事) in 고사성어 means something happened in the past or old story. Many 사자성어s have their own origin. They came from old advices, stories, experiences.
The problem is that these definitions cannot cover every word. There are some 고사성어s which are not 4 characters like 가화만사성(家和萬事成, if your family is in peace, everything goes well), 지음(知音, really close friend), 독서백편의자현(讀書百遍義自見, if you read book one hundred times, the meaning of the words becomes clear). All of them are not 4 characters. They are all 고사성어, but not 사자성어.
Some 사자성어s like 물심양면, 시종일관 have no stories. They are 사자성어 as they are 4 characters, but they are not 고사성어.
Because of this, some people use the word, 한자성어, because all of them are Sino-Korean words. The word 한자성어 can cover everything, but the problem is that it is less frequently used than 고사성어 and 한자성어.
I wrote long article about these words. Actually, many native speakers don't discriminate them. They frequently use 사자성어 and 고사성어 interchangeably. It's almost always safe to use the one you like unless you are in front of 한문 선생님(Chinese Teachers).