Definitions of simple:

• noun:   any herbaceous plant having medicinal properties
• noun:   a person lacking intelligence or common sense
• adjective:   not elaborate in style; unornamented

  Example: "A simple country schoolhouse"

• adjective:   (botany) of leaf shapes; of leaves having no divisions or subdivisions
• adjective:   having few parts; not complex or complicated or involved

  Example: "A simple problem"

• adjective:   easy and not involved or complicated

  Example: "A simple game"

• adjective:   lacking mental capacity and devoid of subtlety
• adjective:   exhibiting childlike simplicity and credulity

  Example: "Simple courtesy"

• name:  A surname (very rare: popularity rank in the U.S.: #78122)