Definitions of pretty:

• adjective:   pleasing by delicacy or grace; not imposing

  Example: "Pretty girl"

• adjective:   (used ironically) unexpectedly bad

  Example: "A pretty mess"

• adverb:   used as an intensifier (`jolly' is used informally in Britain)

  Example: "Pretty big"

• name:  A surname (very rare: popularity rank in the U.S.: #18985)