ci·pher also cy·pher (sīfər)
1. The mathematical symbol (0) denoting absence of quantity; zero.
2. An Arabic numeral or figure; a number.
3. One having no influence or value; a nonentity.
a. A cryptographic system in which units of text of regular length, usually letters, are transposed or substituted according to a predetermined code.
b. The key to such a system.
c. A message written or transmitted in such a system.
5. A design combining or interweaving letters or initials; a monogram.
v. ci·phered, ci·pher·ing, ci·phers also cy·phered or cy·pher·ing or cy·phered
To solve problems in arithmetic; calculate.
1. To put in secret writing; encode.
2. To solve by means of arithmetic.
[Middle English cifre, from Old French, from Medieval Latin cifra, from Arabic ṣifr, from ṣafira, to be empty (translation of Sanskrit śūnyam, cipher, dot); see ṣpr1 in the Appendix of Semitic roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.