1. [n]  a drug that causes contraction of body tissues and canals
2. [adj]  tending to check bleeding by contracting the tissues or blood vessels

STYPTIC is a 7 letter word that starts with S.

1. \Styp"tic\, a. [L. stypticus, Gr. ?, fr. ? to contract.]
   Producing contraction; stopping bleeding; having the quality
   of restraining hemorrhage when applied to the bleeding part;
   astringent. [Written also {stiptic}.]
   
   {Styptic weed} (Bot.), an American leguminous herb ({Cassia
      occidentalis}) closely related to the wild senna.
   
   

2. \Styp"tic\, n. (Med.)
   A styptic medicine.