Are you asking for things that you think are confusing to a beginning gardener? If so, I think "deciduous" is not a familiar term to beginners.

Deciduous = loses its foilage in the fall.

Is that the kind of thing you're looking for? :)

I was originally thinking more of words whose meanings were different when used to discuss plants, but I guess any commonly or semi-commonly used plant-related words and phrases that might be confusing would be OK. Every once in a while, I run into plant-related words that I don't know the meaning of, so I know there are words that are confusing for beginners.

I'm most interested here in words and phrases that might not be as easy to look up as others. Words or phrases that if you typed into google wouldn't just automatically pop up with the correct plant-related definition.

prune (trim) vs. prune (fruit)
stick (rooting a cutting) vs. stick (piece of wood)
warm house vs cool house vs cold house vs cold frame
head house (this one always tickles me for some reason)

What's a "head house"?

It's the building at the end of a greenhouse -- used for potting, office space, whatever. Learned that one at UT. :-) I just like the way it sounds. ;-)