Playfair

noun3

1. •
   an encryption using the Playfair cipher

   • Here's a cipher message. Probably Playfair. — 1932
2. •
   Ellipsis of Playfair cipher.
3. •
   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.

   • 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