In a rapid way:apace, fast, posthaste, quick, quickly. (Informal) flat out, hell-for-leather, pronto. Idioms: full tilt, in a flash, in nothing flat, like a bat out of hell, like a blue streak, like a flash, like a house on fire, like a shot, like a streak, like greased lightning, like the wind, like wildfire. See fast Roget's II The New Thesaurus Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.