Definitions of mental:

• adjective:   involving the mind or an intellectual process

  Example: "Mental images of happy times"

• adjective:   of or relating to the chin- or lip-like structure in insects and certain mollusks
• adjective:   of or relating to the mind

  Example: "Mental powers"

• adjective:   affected by a disorder of the mind

  Example: "A mental patient"

• adjective:   of or relating to the chin or median part of the lower jaw