Real Dictionary

chirp
verb: When a bird or an insect such as a cricket or grasshopper chirps, it makes short high-pitched sounds.

chirp in American English
a short, shrill sound
to make the short, shrill sound of some birds or insects
to utter in a sharp, shrill tone
intransitive verb: to make a characteristic short, sharp sound, as small birds and certain insects
noun: a chirping sound
transitive verb: to sound or utter in a chirping manner

chirp in British English
(esp of some birds and insects) to make a short high-pitched sound
noun: a chirping sound, esp that made by a bird
noun acronym for: Confidential Human Incidents Reporting Programme: a system, run by the RAF Institute of Medicine, by which commercial pilots can comment on safety trends without the knowledge of their employers