Definitions of mad:

• adjective:   roused to anger

  Example: "She gets mad when you wake her up so early"

• adjective:   very foolish

  Example: "A completely mad scheme to build a bridge between two mountains"

• adjective:   marked by uncontrolled excitement or emotion

  Example: "A mad whirl of pleasure"

• adjective:   affected with madness or insanity

  Example: "A man who had gone mad"

• name:  A surname (very rare: popularity rank in the U.S.: #81693)