The Collaborative International Dictionary of English v.0.48:

Screech \Screech\ (skr[=e]ch), v. i. [imp. & p. p. Screeched;
   p. pr. & vb. n. Screeching.] [Also formerly, scritch, OE.
   skriken, skrichen, schriken, of Scand. origin; cf. Icel.
   skr[ae]kja to shriek, to screech, skr[imac]kja to titter, Sw.
   skrika to shriek, Dan. skrige; also Gael. sgreach, sgreuch,
   W. ysgrechio, Skr. kharj to creak. Cf. Shriek, v.,
   Scream, v.]
   To utter a harsh, shrill cry; to make a sharp outcry, as in
   terror or acute pain; to scream; to shriek. "The screech owl,
   screeching loud." --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Screech \Screech\, n.
   A harsh, shrill cry, as of one in acute pain or in fright; a
   shriek; a scream.
   [1913 Webster]

   Screech bird, or Screech thrush (Zool.), the fieldfare;
      -- so called from its harsh cry before rain.

   Screech rain.

   Screech hawk (Zool.), the European goatsucker; -- so called
      from its note. [Prov. Eng.]

   Screech owl. (Zool.)
   (a) A small American owl (Scops asio), either gray or
       reddish in color.
   (b) The European barn owl. The name is applied also to other
       species.
       [1913 Webster]

WordNet (r) 3.0 (2006):

screech
    n 1: a high-pitched noise resembling a human cry; "he ducked at
         the screechings of shells"; "he heard the scream of the
         brakes" [syn: screech, screeching, shriek,
         shrieking, scream, screaming]
    2: sharp piercing cry; "her screaming attracted the neighbors"
       [syn: scream, screaming, shriek, shrieking,
       screech, screeching]
    v 1: make a high-pitched, screeching noise; "The door creaked
         when I opened it slowly"; "My car engine makes a whining
         noise" [syn: whine, squeak, screech, creak,
         screak, skreak]
    2: utter a harsh abrupt scream [syn: squawk, screak,
       skreak, skreigh, screech]