From Longman Dictionary of Contemporary Englishwhoawhoa /wəʊ, həʊ $ woʊ, hoʊ/ interjection 1 used to tell someone to become calmer or to do something more slowly Whoa! You’re driving too fast.2 said to show that you are surprised or that you think something is impressive Whoa. That’s a lot of money.3 DSHused to tell a horse to stop
Examples from the Corpus
whoa• Whoa! Calm down, dude.Origin whoa (1800-1900) ho 