Final answer:
A racial minority is defined by physical characteristics, such as skin color, that society deems significant, distinguishing them from the dominant group and leading to unequal treatment.
Step-by-step explanation:
The kind of minority typically defined by physical characteristics is a racial minority. Sociologist Louis Wirth defined a minority group as 'any group of people who, because of their physical or cultural characteristics, are singled out from the others in the society in which they live for differential and unequal treatment, and who therefore regard themselves as objects of collective discrimination.' In this definition, race refers to superficial physical differences deemed important by a particular society, whereas ethnicity pertains to shared culture.
For example, African Americans in the United States are considered a racial minority due to their distinct physical characteristics.