(1):

(v. i.) To make a short, shrill, cheerful sound; to chirp. See Chirrup.

(2):

(n.) A short, sharp, cheerful noise; a chirp; a chirrup; as, the cherup of a cricket.

(3):

(v. t.) To excite or urge on by making a short, shrill, cheerful sound; to cherup to. See Chirrup.