Definitions of plain:

• noun:   extensive tract of level open land

  Example: "They emerged from the woods onto a vast open plain"

• noun:   a basic knitting stitch
• verb:   express complaints, discontent, displeasure, or unhappiness

  Example: "My mother complains all day"

• adjective:   lacking patterns especially in color
• adjective:   not elaborate or elaborated; simple

  Example: "Plain food"

• adjective:   not mixed with extraneous elements

  Example: "Plain water"

• adjective:   lacking embellishment or ornamentation

  Example: "A plain hair style"

• adjective:   free from any effort to soften to disguise

  Example: "The plain and unvarnished truth"

• adjective:   comprehensible to the general public

  Example: "Written for the popular press in plain nontechnical language"

• adjective:   lacking stylistic embellishment

  Example: "Wrote good but plain prose"

• adjective:   lacking in physical beauty or proportion

  Example: "A plain girl with a freckled face"

• adjective:   clearly apparent or obvious to the mind or senses

  Example: "Made his meaning plain"

• adverb:   unmistakably (`plain' is often used informally for `plainly')

  Example: "You are plainly wrong"

• name:  A surname (rare: 1 in 100000 families; popularity rank in the U.S.: #16401)