Math Dictionary

http://www.amathsdictionaryforkids.com/maths/dictionary
This has animated definitions.

http://intermath.coe.uga.edu/dictnary/homepg.asp
An interactive math dictionary for middle school.

http://www.shodor.org/interactivate/dictionary/
An interactive math dictionary.

http://www.mathwords.com/
Mathwords: Terms and Formulas from Beginning Algebra to Calculus

http://www.themathlab.com/dictionary/dictiona.htm
Math Lab Dictionary.

http://www.math.com/tables/spanish/eng-spa.htm
English Spanish Math Dictionary

http://math2.org/math/es-tables.htm
Dictionary in Spanish

http://www.mathnstuff.com/math/spoken/here/
Math Spoken Here