or chiefly Brit  di*eth*yl*stil*boes*trol  n :  a colorless crystalline synthetic compound C₁₈H₂₀O₂ used as a potent estrogen but contraindicated in pregnancy for its tendency to cause cancer or birth defects in offspring - called also DES , stilbestrol  .
 
   
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2024.