Algebra

Webster's Dictionary

(1): (n.) That branch of mathematics which treats of the relations and properties of quantity by means of letters and other symbols. It is applicable to those relations that are true of every kind of magnitude.

(2): (n.) A treatise on this science.

The Nuttall Encyclopedia

A universal arithmetic of Arabian origin or Arabian transmission, in which symbols are employed to denote operations, and letters to represent number and quantity.