Squeal \Squeal\, v. i. [imp. & p. p. Squealed; p. pr. & vb. n. Squealing.]

[Of Scand. origin; cf. Sw. sqv["a]la, Norw. skvella. Cf. Squeak, Squall.]

1. To cry with a sharp, shrill, prolonged sound, as certain animals do, indicating want, displeasure, or pain.

2. To turn informer; to betray a secret. [Slang]

Source: Webster's Revised Unabridged Dictionary (1913)