I think Mutha Russia phrased it wrong. Im not sure what it is myself, but im guessing Relativism is the idea that any action or idea can be considered good or bad, depending on the person veiwing it, and RIGHTLY considered so. Essentially it opposes the concept of absolute truths, where certain actions or properties are inherently bad.
Thats just a guess, though, correct me if im wrong.
In my personnal opinion, reletavism is just a bunch of crap invented by people to justify their amoral and hedonists tendencies. It is the refuge of the weak willed, who cannot control their impulses. I give in to tempation once in a while, but i realize it is bad and punish myself, i dont try to justify it by saying that the conditions made it ok. There are certain laws that universally apply, and if you break it you are doing wrong. It may have some validity, but its twisted way too much to justify evil, and should be discouraged.
If i ruled the world, I would not tolerate such foolishness! :D