The Collaborative International Dictionary of English v.0.48:
Posthaste \Post`haste\, adv. With speed or expedition; as, he traveled posthaste; to send posthaste. --Shak. [1913 Webster]The Collaborative International Dictionary of English v.0.48:
Posthaste \Post`haste"\, n. Haste or speed in traveling, like that of a post or courier. --Shak. [1913 Webster]