Algebraic expression: A given set of letters called variables, and real numbers called constants that are combined using addition, subtraction, multiplication, division and/or exponentiation.

Constant: It is a number or value that remains always the same. Never changes.

Exponent: It is a raised number representing the repeated multiplication of a given factor.

Perfect square trinomial: A trinomial generated by the product of two equal binomials.

Expression: Any combination of numbers and operations without the = sign. 

Factors: All whole numbers that are multiplied together to yield another number.

Like terms: Terms that have the same combination of variables to the same power as factors.

Negative square root: The opposite root to the principal root of the square root.

Operation: Any action we perform on one or two numbers to produce a new number. Most common ones are addition, subtraction, multiplication, division, square roots, powers, and so on.

Polynomial: An algebraic statement with one or more terms. Word comes from “poly” which means many.

Power: Exponent of a number or variable.

Principal root: Given a number with two roots, the positive root is the principal and its given by the radical sign.

Rational exponent: Given that the nth root of x is a real number and m is an integer, we have that x^1/n = ⁿÖx and x^m/n = ⁿÖx^m= (ⁿÖa)ⁿ

Rational number: Any number that may written as a fraction; including whole numbers (written as fractions with 1 as denominator) and decimals that truncate or repeat (may be expressed as fractions).

Rationalize the denominator: The process of changing the denominator of a fraction from radical expression to rational number without changing the value of the expression.

Real number: Any number rational or irrational.
With exception of the imaginary numbers all numbers are real numbers.

Reciprocal: Multiplicative inverse of a number different than zero. The multiplication of a number and its inverse is 1.

Subtraction: Adding the opposite