What does 원님 mean?

ANSWER:  원님 (員님) was the polite way to address the administrative heads of towns, counties, and districts in the provinces during the Joseon Kingdom era. The 원(員) comes from 관원(官員), which means government official, and 님 is a polite suffix that was added to 원(員) to make it a polite form of address.

The following video tells the story of an official (원님) who came face to face with a ghost during the Yi Dynasty (Joseon Kingdom). The official had just been assigned to be the administrative head (원님) of Cheonwang-dong (천왕동), which was a place that is now located in the Guro District (구로구) of Seoul. The official came face-to-face with a ghost named 하연(河演), who had previously been a prime minister during the time of King Sejong and had recently died. The ghost came to complain about people illegally cutting down trees near his grave. Though the ghost had visited previous officials (원님) of Cheonwang-dong to ask their help, they had all been so terrified upon seeing the ghost that they all fainted and died. This official was the first that was brave enough to face the ghost and hear his grievance. Meanwhile, an innocent man was awaiting execution for the deaths of the previous officials.

There is a problem in the last sentence of the Korean story since it was written as if the magistrate received the pardon instead of the man who had been falsely accused of murdering the previous magistrates. In the translation, I fixed it by filling in the subject of the final clause.

"천왕동 하정승 설화"

"The Tale of Cheonwang-dong's Minister Ha"

옛날 옛적 천왕동에서 있었던 일이에요. 이 곳에 원님이 부임하면 당도한 첫날밤에 죽는 일이 계속 일어났어요. 나라에서는 걱정이 이만저만 아니었답니다. 그래서 사형 선고을 받은 사람을 이 곳 원님으로 보내기로 했어요. 

This happened in Cheonwang-dong long, long ago. Whenever a new magistrate was assigned to this place, each would die on the first night after his arrival, causing no small amount of anxiety in the country. This resulted in a man receiving a death sentence and being scheduled to appear before the magistrate of this place.

새롭게 부임하게 된 원님은 첫날밤 촛불을 밝히고 무슨 일이 일어날까 걱정하며 기다리고 있었어요. 밤이 깊어지자 갑자기 촛불이 휙 꺼졌고 눈 앞에 한 선비가 나타났어요.

On his first night, the newly assigned magistrate had the candle fire burning brightly as he anxiously waited for something to happen. Late in the night, the candle fire was suddenly swooshed out, and a scholarly gentleman appeared before the eyes of the magistrate.

그 선비는 자신의 묘에 자꾸 도벌꾼이 들어와 나무를 마구 베어 가고 있다고 말했어요. 그리고 원님이 일을 막아내 준다면 그 선비도 원님을 도와주겠다고 했어요. 

The gentleman said that tree thieves were frequently coming to his grave and indiscriminately chopping down the trees there and carrying them away. And he said that if the magistrate would stop it from happening, he would help the magistrate. 

원님은 도벌꾼들을 찾아내서 벌을 주었고 죄를 사면 받게 되어 행복하게 살았답니다. 

It is said that the magistrate caught and punished the tree thieves, and that [the innocent man] was pardoned and lived happily ever after.