Definitions of sick:

• noun:   people who are sick

  Example: "They devote their lives to caring for the sick"

• verb:   eject the contents of the stomach through the mouth
• adjective:   not in good physical or mental health
• adjective:   feeling nausea; feeling about to vomit
• adjective:   affected with madness or insanity
• name:  A surname (very rare: popularity rank in the U.S.: #25098)