Definitions of human:

• noun:   any living or extinct member of the family Hominidae
• noun:   a human being
• adjective:   having human form or attributes as opposed to those of animals or divine beings

  Example: "Human beings"

• adjective:   characteristic of humanity

  Example: "Human nature"

• adjective:   relating to a person

  Example: "The experiment was conducted on 6 monkeys and 2 human subjects"

• name:  A surname (rare: 1 in 100000 families; popularity rank in the U.S.: #17725)