Definitions of unsuitable:

• adjective:   not appropriate for a purpose or occasion

  Example: "Unsuitable attire for the office"

• adjective:   not meant or adapted for a particular purpose

  Example: "A solvent unsuitable for use on wood surfaces"

• adjective:   not conducive to good moral development

  Example: "The movie is unsuitable for children"

• adjective:   not capable of being applied
• adjective:   not worthy of being chosen (especially as a spouse)