Definition of "hilloa"

"Hilloa, brother," quoth [Friar] Tuck, "let me aid thee." So saying, he took the key from the other's hand and quickly opened the door with a turn of it.

1883, Howard Pyle, “Robin Hood Compasseth the Marriage of Two True Lovers”, in The Merry Adventures of Robin Hood […], New York, N.Y.: […] Charles Scribner’s Sons […], part fourth, page 146

As for Dick, he looked at her admiringly a while, and then said at last: "Well, Clara, I do wish we were there! But, hilloa! we are getting back way."

1890, William Morris, chapter XXII, in News from Nowhere‎

'Ah,' muttered Todd to himself, 'I like boys of a religious turn. They are much easier managed, for the imagination in such cases has been cultivated at the expense of the understanding. Hilloa, who have we here?'

1847, James Malcolm Rymer, Thomas Peckett Prest, chapter 32, in The String of Pearls‎

I heard old Jenkins, scarcely recovered from the effects of his potations, hilloaing at the top of his voice for Julia

1836, James White, The adventures of Sir Frizzle Pumpkin, Nights at mess, and other tales