Answer:
Those words refer to the degree, or highest exponent that modifies a variable, or the polynomial.
Constant=No variables in the polynomial
Linear=Variable raised to the first power
Quadratic=Variable raised to the second power (or "squared")
Cubic=Variable raised to the third power (or "cubed")
Quartic=Variable raised to the fourth power
Quintic=Variable raised to the fifth power
Anything higher than that is known as a "6th-degree" polynomial, or "21st-degree" polynomial. It all depends on the highest exponent in the polynomial. Remember, exponents modifying a constant (normal number) do not count.