interjection, noun, plural hal·loas, verb (used with or without object), hal·loaed, hal·loa·ing.
Examples from the Web for halloa
I called to him, and I thought I heard him answer, “Halloa, who calls?”Old Jack|W.H.G. Kingston
Then suddenly some one struck something hard, and cried "Halloa!"The Maid of Sker|Richard Doddridge Blackmore
The night-porter looked through a small grating in the portal with a surly eye, and cried 'Halloa!'Barnaby Rudge|Charles Dickens
Bickers would never see him till he came close up, and then Marky would have the sack on in two twos before he could halloa.The Master of the Shell|Talbot Baines Reed
I knocked my toe against a rock, just now, and it was as much as I could do not to halloa.With Wolfe in Canada|G. A. Henty