Ethnocentrism is a commonly used word in circles where ethnicity, inter-ethnic relations, and similar social issues are of concern. The usual definition of the term is "thinking one's own group's ways are superior to others" or "judging other groups as inferior to one's own." Ethnocentrism can be more specifically defined as, "making false assumptions about others" ways based on our own limited experiences." The key word is assumptions; because we are not even aware that we are being ethnocentric, we don't understand that we don't understand.
The definition given above emphasizes that we make false assumptions based on our own limited experience. If our own experience is the only "reality" we have, then it is normal to assume it is the "natural" basis of reality. And our own ways work for us. Our perceptions of colors, values, our social roles, our beliefs about life and the universe, and all our other ways help us organize life experience and provide important meanings and functions as we move through daily and life span activities. It is normal to assume these provide a meaningful and functional basis for life in general.
One example of ethnocentrism that I experienced during the week was the other day I pulled my car up to my apartment to drop off some groceries. As I was unloading the car the resident advisor had opened his door to see if his Chinese food had arrived. Usually food delivery people pull right up to your door. The R.A. told me he thought I was the person delivering his food because he heard the car and thought his food had arrived. As I was driving away someone pulled up to the door, at that moment my roommate said, "that must be his Chinese food," he said this, and I though it to myself because the driver was Chinese. It turned out that it was the Chinese delivery person. .
This type of remark would be considered ethnocentric because it assumes that because, in this case, that must be the Chinese food because the driver is Chinese.