I. ˈ(h)wō, ˈhō verb imperative
also wo or woa ˈwō
Etymology: Middle English whoo, who
— a command to a draft animal to stand still; compare giddap
II. verb imperative
: cease or slow a course of action or a line of thought : pause to consider or reconsider — often used to express a strong reaction (as alarm or astonishment)