Definition of "halloa"

halloa

/hɛˈloʊ/

interjection
1. A loud exclamation; a call to invite attention to something or to incite; a shout.
  Quotations
  "Halloa! Below there!" When he heard a voice thus calling to him, he was standing at the door of his box, with a flag in his hand, furled round its short pole.
  1866, Charles Dickens, The Signal-Man‎
  "Halloa! Stop there!" he shouted, holding his bicycle to block our road.
  1903 December 26, A[rthur] Conan Doyle, “The Adventure of the Solitary Cyclist”, in The Return of Sherlock Holmes, New York, N.Y.: McClure, Phillips & Co., published February 1905
verb
third-person singular simple present halloas, present participle halloaing, simple past and past participle halloaed
1. (intransitive) To utter an exclamation of "halloa".