Hal‐loo″ (hăl‐lo͞o″), n. [Perh. fr. ah + lo; cf. AS. ealā, G. halloh, F. haler to set (a dog) on. Cf. Hollo, interj.] A loud exclamation; a call to invite attention or to incite a person or an animal; a shout.
List! List! I hear
Some far off halloo break the silent air. Milton.