noun

1. a mathematical system using symbols, esp. letters, to generalize certain arithmetic operations and relationships (Ex.: x + y = x represents a unique relationship between x and y, and has an infinite number of examples, as 3 + 6 = 9)
2. any of various symbolic mathematical systems having formal rules of operation, defined relationships, finite processes, etc. Boolean algebra
3. a textbook or treatise dealing with algebra

Etymology: ME < ML < Ar al-jabr, the reunion of broken parts < al, the + jabara, to reunite