adj. 25B6; adjective
a speedy reply : RAPID, swift, quick, fast; prompt, immediate, expeditious, express, brisk, sharp; whirlwind, lightning, meteoric; hasty, hurried, precipitate, breakneck, rushed; informal p.d.q. (pretty damn quick), snappy, quickie.
a speedy hatchback : FAST, high-speed; informal nippy, zippy; poetic/literary fleet.
slow.