What does the word "Racism" really mean?

Lately, the word "Racism" has featured a number of times in the news. Anything uttered by a "foriegner" ie, foreign to the country that the individual may be visiting, is being construed as "Racist" remarks! What does the word "Racism" really mean? Are we becoming overly sensitive and exaggerating the actual circumstances of the incident? 

According to Wikipedia :- "Racism is a belief system or doctrine which postulates a hierarchy among various human races or ethnic groups. It may be based on an assumption of inherent biological differences between different ethnic groups that purport to determine cultural or individual behaviour."

Now, keeping this definition in mind, let's look again at the whole "Symonds vs Harbhajan" racism episode. Harbhajan Singh probably uttered a few expletives or called Symonds a "Monkey" in a fit of rage or frustration, whatever the case may be. Now, we as kids have done it a number of times too. I remember calling out to any number of kids to tease them that they are "monkeys and donkey". These two words are quite commonly uttered by each and every individual in our country right from our childhood! Does that mean that we were "Racist"? We were not even aware of the existence of such a word! So, What exactly is so "Racist" about the word "Monkey" may I ask? Will somebody please clarify! Besides the fact that Andrew Symonds does indeed look like a monkey on the field with the white colored cream that he applies on his lips! If, he had asked me the question in his dressing room in the morning, "How do I look?" I would have answered, " You look like a monkey!" That would be an honest opinion. Now, would you call that "Racist"? Now, if somebody in his own team called him a monkey, would that also qualify as a "Racist" comment? 

Indians, on the other hand have been used to being the victims of racism for centuries at the hands of the British and other such Foriegn rulers who came to our country and forced their "white" skin upon us! I find this whole episode of tagging the word "racism" to Indians, very ironic and out of sync! Indians have been quietly suffering all the insults and humiliation for centuries, We Don't Need To Do So Anymore! The Indian Cricket Team should stop playing any further matches and return to India, till the Australians learn to play a fair game, in the true sportsman spirit.