"Ho! who's within?" Shak. 2. [Perhaps corrupted fr. hold; but cf. F. hau stop! and E. whoa.] Stop! stand still! hold! -- a word now used by teamsters, but formerly to order the cessation of anything. [Written also whoa, and, formerly, hoo.]

The duke . . . pulled out his sword and cried "Hoo!"

An herald on a scaffold made an hoo.

A stop; a halt; a moderation of pace.

Halloo! attend! -- a call to excite attention, or to give notice of approach.