Webster's Revised Unabridged Dictionary · 1913

Hollo

Hollo , interjection and noun

[See Halloo, and compare Holla.]

Ho there; stop; attend; hence, a loud cry or a call to attract attention; a halloo.
And every day, for food or play, Came to the mariner's hollo. — Coleridge

Hollo , intransitive verb

[See Hollo, interj., and compare Halloo.]

To call out or exclaim; to halloo.