One who is just starting to learn or do something
He was no greenhorn, but what was he doing in the desert?
Probably another greenhorn Pete had to pull out of a scrape.
Of course, even a greenhorn could follow the wagon tracks they would leave in the sand.
Maybe he wasn't a saddle bum, but only a greenhorn would think he could live off the barren land that surrounded them.
Or you can be lazy and choose Greenhorn.