Trăn'quil-īz'er or Trăn'quil-līz'er, n.
n. 1. One who, or that which, tranquilizes.
Sense 2. Specifically, a kind of chair in which a raving maniac may be so fixed as to be motionless. It is used for the production of tranquillity, in a paroxysm of raving.