I don't have an all-encompassing definition for "racism" because, like colour, it needs to be experienced and can't be easily described.
As in the example below.
If you were in China (and you were not Chinese) would you like some local whom you don't know, referring to you as a "foreign devil"?
If it were meant as a joke from someone whom you knew, it signals that you had relaxed in each other's company to the point of being able to joke about a difference in background, ethnicity or culture.
But when used by a stranger, it is generally used to exclude, dimish and demonify a fellow human being.
So if you were to experience this, you would then take a great deal of care not to refer to a Chinese person whom you don't know back home in a similar dismissive way - "chin k, go ok etc".
So I have no definition for racism, but I can offer an example of it and a method for avoiding it.
What you yourself find hateful, do not inflict upon others.
(Sir) Lunchalot - in fair round belly with good capon lined
