A greenhorn is a new, inexperienced person who is just starting out in a particular situation.
Part of speech:
(Countable nouns, like "bottle," "piece," and "decision," are words for things that can be broken into exact units. You talk about "a bottle," "three pieces," and "many decisions."
Likewise, talk about one greenhorn or multiple greenhorns.)
Even though it's usually a noun, you can use "greenhorn" like an adjective.
Greenhornism is the state of being a greenhorn. And, a greenhornism is something you do that reveals how new or inexperienced you are.
How to use it:
The tone of this word can be neutral or slightly negative. When you call people greenhorns, you might be hinting that they're clumsy, clueless, easily fooled, or even useless. And because we first used "greenhorn" to describe newly enlisted soldiers, the word still has a whiff of the military to it. But we also use it to describe newly arrived immigrants, as well as people who are just starting out in their jobs or their hobbies.
So, call someone a greenhorn, or talk about greenhorns as a group: "his bumbling errors marked him as a greenhorn," "I still had the misplaced confidence of a greenhorn," "she looks down on all these greenhorns."
When you're using "greenhorn" like an adjective, you can talk about greenhorn people (like greenhorn soldiers and greenhorn beginners), or people in a greenhorn state, stage, or phase.
examples: Send help: our leader is a greenhorn who's ignorant of his responsibilities and unwilling to learn them.
We were greenhorn freshmen back then, writing our locker combinations with Sharpies on our Converses, slipping red-faced into the guidance office because we lost the printout of our class schedules (again).