Source : Webster's Revised Unabridged Dictionary (1913)

Shrill \Shrill\, a. [Compar. {Shriller}; superl. {Shrillest}.]
   [OE. shril, schril; akin to LG. schrell, G. schrill. See
   {Shrill},v. i.]
   Acute; sharp; piercing; having or emitting a sharp, piercing
   tone or sound; -- said of a sound, or of that which produces
   a sound.

         Hear the shrill whistle which doth order give To sounds
         confused.                                --Shak.

         Let winds be shrill, let waves roll high. --Byron.

Shrill \Shrill\, n.
   A shrill sound. [Obs.] --Spenser.

Shrill \Shrill\, v. i. [imp. & p. p. {Shrilled}; p. pr. & vb. n.
   {Shrilling}.] [OE. schrillen, akin to G. schrillen; cf. AS.
   scralletan to resound loudly, Icel. skr["o]lta to jolt, Sw.
   skr["a]lla to shrill, Norw. skryla, skr?la. Cf. {Skirl}.]
   To utter an acute, piercing sound; to sound with a sharp,
   shrill tone; to become shrill.

         Break we our pipes, that shrilledloud as lark.
                                                  --Spenser.

         No sounds were heard but of the shrilling cock.
                                                  --Goldsmith.

         His voice shrilled with passion.         --L. Wallace.

Shrill \Shrill\, v. t.
   To utter or express in a shrill tone; to cause to make a
   shrill sound.

         How poor Andromache shrills her dolors forth. --Shak.

Source : WordNet®

shrill
     adj : high-pitched and sharp; "piercing screams"; "a shrill
           whistle" [syn: {piercing}, {sharp}]

shrill
     v : utter a shrill cry [syn: {shriek}, {pipe up}, {pipe}]