Webster's New World Student Dictionary:
1. one of the major groups or populations into which all human beings are divided based on certain inherited biological characteristics, such as blood types, resistance to particular diseases, body shape, and skin colour.
2. any large group of living creatures.
3.a group of people who have something in common.
This word comes to us, through French, from Italian [I]razza[I] meaning "one of th emajor groups of human beings." Its source is not known.