A free app for Android, by MobiSystems.

The Oxford Mathematics Dictionary is a free-to-download, comprehensive, and authoritative dictionary app for all your mathematical needs.

This is the most advanced and user-friendly app available for Android.

You will find detailed definitions for over 3,000 mathematical terms and concepts, as well as advanced search and language tools to help you find what you are looking for quickly and easily.

You can search across multiple disciplines. There are definitions for:

Linear algebra

Optimization

Nonlinear equations

Differential equations

Fractals

Game theory

Chaos

Major mathematicians

Fields’ medals

Inequalities

Moments of inertia

Roman numerals

And more

This is an app that is both fun and educational.