Subject: What is the definition of a 'true nut'?

Dear Sirs:

Hello, my name is Melinda Gray, and I am a junior at the Arkansas School 
for Mathematics and Sciences.  I'm working on a science fair project 
titled "The Effects of Nut Extracts on Plants."  In the introduction 
section of my project, I would like to include the definition of a "true 
nut."  I have searched the Internet and various libraries in my area, but 
I have been unable to find the definition.  Would you be able to help me 
with this?

Thank you!
Melinda Gray

Re: What is the definition of a 'true nut'?