Source : Webster's Revised Unabridged Dictionary (1913)

High-pressure \High"-pres`sure\ (?; 135), a.
   1. Having or involving a pressure greatly exceeding that of
      the atmosphere; -- said of steam, air, water, etc., and of
      steam, air, or hydraulic engines, water wheels, etc.

   2. Fig.: Urgent; intense; as, a high-pressure business or
      social life.

   {High-pressure engine}, an engine in which steam at high
      pressure is used. It may be either a condensing or a
      noncondensing engine. Formerly the term was used only of
      the latter. See {Steam engine}.

Source : WordNet®

high-pressure
     adj : aggressively and persistently persuasive; "a hard-hitting
           advertising campaign"; "a high-pressure salesman" [syn:
            {hard-hitting}]