interjection, noun, plural hul·loos, verb (used with or without object), hul·looed, hul·loo·ing.
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for hulloo
"Hulloo, Rob, come on," was Roy's exclamation as he caught sight of his friend.
Sir Bryan, undeterred by these suggestions of his fancy, lifted up his voice and shouted "Hulloo!"