polyalphabetic substitution

[ pol-ee-al-fuh-bet-ik suhb-sti-too-shuhn, ‐-tyoo-shuhn, pol-ee- ]

noun

, Cryptography.

1. a system of substitution that mixes together a number of cipher alphabets in a cryptogram so that each plaintext letter is represented by a cipher that repeatedly changes.

Word History and Origins

Origin of polyalphabetic substitution¹

1935–40; poly- + alphabetic ( def )