Playfair

(This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium.)

• (craters): The craters are Named after Scottish mathematician, scientist and C of S minister John Playfair
• (cipher): The cipher is Named after British Lord, baron, politician and scientist Lyon Playfair, who popularized the cipher.

Playfair (countable and uncountable, plural Playfairs)

1. A surname.
2. A placename
   1. A number of craters in Solar System.

      Synonyms: Playfair Crater, Crater Playfair

      1. A crater in Mars, Solar System.
      2. A crater in Moon, Earth-Moon System, Solar System.

Playfair (countable and uncountable, plural Playfairs)

1. (cryptography) Ellipsis of Playfair cipher.
2. (cryptography) an encryption using the Playfair cipher
   • 1932, Dorothy Sayers, Have His Carcase‎^[1]:

     Here's a cipher message. Probably Playfair.

3. (crosswording) A 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.
   • 1977, Games & Puzzles:

     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 .

   • 2021 December 22, Azed, “No. 2,740 ‘Christmas Playfair’ - Competition Puzzle”, in The Guardian‎^[2]:

     see title

• Fairplay, fair play