Check out these websites to find definitions of math terms and other helpful resources:

Math Glossary by Hartcourt School Publishers
Do you want to find out what the word “addend” means? Find the definition of math words or terms for your grade level.

Math Words: Terms and Formulas
An interactive math dictionary with enough words, terms, formulas, pictures, diagrams, tables and examples to make your inner math geek happy!

Math League
Get ready to organize your own math contest! Find questions for your own math contest for grades 4 and up.