riddle in WordNet English dictionary

1. a difficult problem
   riddle  conundrum  enigma  brain-teaser 
   
2. a coarse sieve (as for gravel)
   riddle 
   

1. spread or diffuse through
   "An atmosphere of distrust has permeated this administration"; "music penetrated the entire building"; "His campaign was riddled with accusations and personal attacks"
   permeate  pervade  penetrate  interpenetrate  diffuse  imbue  riddle 
   
2. explain a riddle
   riddle 
   
3. set a difficult problem or riddle
   "riddle me a riddle"
   riddle 
   
4. speak in riddles
   riddle 
   
5. pierce with many holes
   "The bullets riddled his body"
   riddle 
   
6. separate with a riddle, as grain from chaff
   riddle  screen