Playfair

plural Playfairs

1. countableuncountableA surname.
2. countableuncountableA placename
   1. countableuncountableA crater in Mars, Solar System.

      Synonyms: Playfair Crater, Crater Playfair

   2. countableuncountableA crater in Moon, Earth-Moon System, Solar System.

      Synonyms: Playfair Crater, Crater Playfair

plural Playfairs

1. abbreviationcountableellipsisuncountablecomputingEllipsis of Playfair cipher.
2. countableuncountablecomputingan encryption using the Playfair cipher

   Here's a cipher message. Probably Playfair.

   1932, Dorothy Sayers, Have His Carcase

3. countableuncountablecrosswordingA form of crossword in which some words must be encrypted with a Playfair cipher before being inserted into the grid, and solvers must deduce the codeword and the encrypted clues.

   see title

   2021 December 22, Azed, “No. 2,740 ‘Christmas Playfair’ - Competition Puzzle”, in The Guardian^(https://uploads.guim.co.uk/2024/12/21/AZ_2740_(22nd_December).pdf)

   1 more example

   But what about Playfair puzzles ? One must reckon to solve at least three of the Playfair clues independently before cracking the code and getting checking to help with solving the fourth .

   1977, Games & Puzzles