The Collaborative International Dictionary of English v.0.48:

Searching \Search"ing\, a.
   Exploring thoroughly; scrutinizing; penetrating; trying; as,
   a searching discourse; a searching eye. "Piercing, searching,
   biting, cold." --Dickens.
   [1913 Webster] -- Search"ing*ly, adv. -- Search"ing*ness,
   n.
   [1913 Webster]