Definitions of riddle:

• noun:   a coarse sieve (as for gravel)
• noun:   a difficult problem
• verb:   set a difficult problem or riddle

  Example: "Riddle me a riddle"

• verb:   explain a riddle
• verb:   speak in riddles
• verb:   pierce many times

  Example: "The bullets riddled his body"

• verb:   separate with a riddle, as grain from chaff
• name:  A surname (common: 1 in 7142 families; popularity rank in the U.S.: #871)