From prompt +‎ -ly.

• (General American) IPA^(key): /ˈpɹɑmptli/
• (Received Pronunciation) IPA^(key): /ˈpɹɒmptli/

• Audio (US):

  (file)

• Hyphenation: prompt‧ly

promptly (comparative more promptly, superlative most promptly)

1. In a prompt manner.
   1. Both soon and quickly.
      • 1943 November – 1944 February (date written; published 1945 August 17), George Orwell [pseudonym; Eric Arthur Blair], Animal Farm[…], London: Secker & Warburg, published May 1962, →OCLC:

        […] the ducklings nestled down inside it and promptly fell asleep.

      • 2011 May 11, Sam Leith, “Sam Leith's top 10 alternative realities”, in The Guardian‎^[1], archived from the original on 7 March 2021:

        After being kidnapped by a seagoing ne'er-do-well, its Lady protagonist finds herself drifting through a passage at the North Pole into a wholly different world, with its own sun, moon and stars, and a population of bear-men, bird-men and fox-men who promptly make her Empress. Win!

   2. Exactly at a specific time.

      The sale will begin on January 28th, promptly at 9 a.m.

• on line; see also Thesaurus:punctually