quad in WordNet English dictionary

1. a muscle of the thigh that extends the leg
   quadriceps  quadriceps femoris  musculus quadriceps femoris  quad 
   
2. a rectangular area surrounded on all sides by buildings
   quad  quadrangle 
   
3. (printing) a block of type without a raised letter; used for spacing between words or sentences
   quad  space 
   
4. one of four children born at the same time from the same pregnancy
   quadruplet  quad