A greenhorn is someone who lacks experience of something — a new person who has not learned the ropes yet. The word is informal, a little old-fashioned or colourful, more American than British in feel today, and it can sound teasing. It is not always unkind, but it can make a new person feel watched. Green here does not mean the colour of a shirt or of grass. In older English, green meant fresh, young, not yet ready — people said it of new wood, new cheese, new leather, even of wounds. A green horn was first a young animal's horn, or a horn still fresh; later, from the 1600s, people used it for a person who was still fresh at a job. You can be a greenhorn at work, at a sport, or in a new country. It is about lack of experience, not about being foolish by nature, and it has nothing to do with real horns on a head.

新手、生手、菜鳥（帶點調侃；不是真的有角，也不是衣服是綠色）