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]

WordNet (r) 3.0 (2006):

screeching
    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]