Designating imaginary or hypothetical footwear that enables the wearer to travel an extremely long distance very rapidly and unimpeded by any…

Esp. of pace: very fast or rapid. Now rare.

wearing or as if wearing seven-league boots; making or characterized by extremely rapid progress.

Extremely fast; very rapid.

Modifying adjectives denoting speed or swiftness, with the sense ‘as —— as lightning’, as in lightning-fast, lightning-quick, lightning-rapid, etc.

Moving or operating very quickly; relating to, facilitating, or used in a fast process or at a high speed of operation.

In double-quick time.

Travelling at a rate of a mile a minute; (figurative) extremely rapid.

= high-speed, adj.; express boiler, a boiler capable of getting steam up with great rapidity; express highway, etc.: see expressway, n.; express lift…

figurative. Very fast, frenzied.

colloquial. Very fast indeed, high-speed.

hyperbolically. Extremely fast.