monoalphabetic substitution

[ mon-oh-al-fuh-bet-ik suhb-sti-too-shuhn, mon-oh- ]

noun

, Cryptography.

1. a system of substitution that uses only one cipher alphabet in a cryptogram so that each plaintext letter is always represented by the same cipher.

Word History and Origins

Origin of monoalphabetic substitution¹

1935–40; mono- + alphabetic ( def )