IPA: /ˈɡriːnhɔːrn/
KK: /ˈɡrinˌhɔrn/
A person who is new and lacks experience in a particular area or group.
As a greenhorn in the industry, she was eager to learn from her more experienced colleagues.
Greenhorn → The word is formed from "green" (meaning inexperienced or new) and "horn" (from Old English "horn", meaning a projection or appendage). The term originally referred to a young animal with horns that had not yet matured, and by extension, it came to describe a person who is new and inexperienced in a particular field or activity.
Think of someone who is 'new' ('green') and still 'growing' into their role, just like a young animal with 'horns' that are not fully developed.