Using words they might not know?

What do you think about writing a YA novel, one that appeals to 10-14 year-olds, in which there are words some readers won't know? This could be jargon for a particular hobby/industry or even just regular, every day words they might have to look up (not necessarily hard, "grown up" words, but just words they may not encounter in every day life).

This sounds stupid, but hopefully it makes sense. I'd like your responses before I get more specific.

Thanks so much for your replies. How often do you think readers in this age group come across words in their books they don't know, and look them up or ask about them if they don't know them?

Thank you all so much. You've made me very comfortable with the decision I made about my book.

OK, I think I'll give some more details now. The issue I had was a disagreement with the editor on my horsey novel. There were two words (jargon) she didn't know and wanted me to explain them in the story. I was reluctant to do this, because:

a) it would have been awkward
b) knowledge of the word didn't hamper the understanding of the story IMO as well as the opinion of another reader who does not know anything about horses
c) they're easy words to look up (and very common horsey words if you read horsey books)
d) the majority of people who buy this book are likely to either know horses or read enough horsey books that they'd know the words anyway and I didn't want to bore or alienate my readers
e) there could be other words in the book the reader doesn't know, say "exclaim" or "chuckle." Surely I can't anticipate all of them and define them all. It would just get ridiculous...The Series of Unfortunate Events did that, but that was the whole premise of the books, so it worked for them
f) other books in this genre don't define every single word
g) there are scenes later in the book where it becomes clearer what these words mean. I'd be willing to bolster those to make it clearer, because I could do that without bogging down the story, but it would just be awkward where the words first appear.

Any thoughts, given this new information? I wanted to keep it as unbiased as possible for your initial reactions.

I just picked two words that are just regular words as an example. Considering some readers could be as young as 9 or 10, there has to be some non-jargon words in the book they don't know. My point is, kids just don't know all the words adults do, so you're bound to have some they don't.

The words in question were "longe" (a means of exercising a horse, where it goes in circles around you on a long line) and "girth" (a band that holds the saddle on by being buckled to the saddle at each end, passing under the horse's belly).

I have a scene where the MC longes a horse and I describe what's happening, and there are several mentions of someone buckling up their girth or unbuckling it and removing the saddle.

Thanks! Lunge and longe are different spellings for the same word and equally acceptable. It's first used in context as something the MC does to horses. Girth is used in context as a piece of tack, so I don't think it could be misinterpreted.

I know it's hard to answer the question without reading the actual book, so I appreciate your thoughts! Hopefully I've clarified enough.