When there are three terms, it's a trinomial:

x^2 - x - 6

So, what about four terms?  Quadnomial?  Naw, we don't go there.  Too hard to pronounce.

This guy is just called a polynomial:

7x^3 + 5x^2 - 2x + 4

There's one more word I need to tell you about:

degree

Here's how you find the degree of a polynomial:

Look at each of the terms...
Whoever has the most letters wins!

Check it out:

This is a 5th degree polynomial:

3x^2 - 8x^4 + x^5
This guy has 5 letters...
The degree is
5.