n. A shrill noise, especially made by a voice or bird; a yell, scream, or call.n. A four-digit transponder code used by aircraft for identification or transmission of emergency signals.n. An issue or complaint related to aircraft maintenance.n. The American night heron.v. To make a squawking noise; to yell, scream, or call out shrilly.v. To speak out; to protest.v. To report an infraction; to rat on or tattle; to disclose a secret.v. To set or transmit a four-digit transponder code. (Normally followed by the specific code in question.)