I would simply show her the definition of the word, and ask whether you had used it incorrectly.
In one of my advanced economics courses, the professor was replaced with a grad student for the semester. When I got the mid-term exam, I was baffled. Usually mid-terms at that school were two hours long, and you were hard pressed to finish in two hours in an advanced course. I finished the mid-term exam in 15 minutes. Maybe less. I had to ask if my exam was missing some pages.
I got my paper back with "D" on it, for "not showing my work." I'd earlier had one of those beastly professors that would mark an entire question wrong if you left off so much as one unit of measure (good training, by the way, hated it at the time though) ... so there was no way I'd left off a thing in my answer.
As it turned out, the grad student teaching this advanced course was completely unfamiliar with basic calculus. He'd come up with a tough set of problems to solve without calculus, but a simple matter with it. I suppose if you've never seen it before, you'd look at a problem someone solved with differential methods and say "How did they get from there to here? They didn't show their work!" and that's how I got a "D."
The academic policy was that unless a particular method was stated, any method could be used to solve an exam problem, so I was in the clear on using calculus. I had to appeal to the department head. I was given an "A", and the grad student had to explain how he'd gotten that far without the math skill essential to his chosen field of study.
If you're going to go on in school, expect to need to politely question a grade from time to time. Things like this happen, and nobody knows everything, not even your teachers, not at any level. Take it as an opportunity to show your teacher how much learning you're doing outside of school. Be polite, and give your teacher an opportunity to correct their error without being made to feel foolish.