cipher

American  

[sahy-fer] / ˈsaɪ fər /

noun

1. a secret method of writing or recording data, such as by substituting or adding letters or numbers, using specially formed symbols, or the like; code.

   The spies exchanged messages using a complex cipher.

   The encryption software creates unbreakable ciphers for secure communication.

2. writing, or a piece of writing, done by a secret method; a coded message.

   Hostile agents intercepted the cipher and began trying to figure out its meaning.

3. the key to a secret method of writing.

   After a year of studying the coded messages, the analysts were no closer to discovering the cipher.

4. someone or something that is not understood; mystery or enigma.

   I just can’t figure him out—he’s a complete cipher to me.

5. zero.

6. a person or thing of no influence or importance; nonentity.

   Having lost the party leadership, she is now a mere cipher on the political scene.

7. Usually cypher

   1. a performance by a group of rappers, hip-hop artists, or break dancers who take turns improvising individual verses, dances, etc.

   2. an individual verse, dance, etc., that is part of such a performance.

8. any of the Arabic numerals, such as 1, 2, or 3, or any number written with such numerals, such as 476.

9. Arabic numerical notation collectively.

   The date is MXML in Roman numerals, or 1950 in cipher.

10. a combination of letters, such as the initials of a name, in one design; monogram.

    The cipher for Queen Elizabeth II had an E entwined with an R for regina, Latin for “queen,” on either side of a Roman numeral II.

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verb (used without object)

1. to use figures or numerals arithmetically; do arithmetic.

   He had never learned to read or write, but he could cipher.

2. to write messages in or as if in a secret code.

verb (used with object)

1. to convert into code; encrypt.

   The program works by ciphering or scrambling the data.

2. to figure out the meaning of; interpret or decode (often used without ).

   Using a good phrase book, the tourist was able to cipher out what people were saying.

3. to calculate numerically; figure (often used without ).

   I tried to cipher out the interest on the loan, compounded over five years.

cipher British  

/ ˈsaɪfə /

noun

1. a method of secret writing using substitution or transposition of letters according to a key

2. a secret message

3. the key to a secret message

4. an obsolete name for zero

5. any of the Arabic numerals (0, 1, 2, 3, etc, to 9) or the Arabic system of numbering as a whole

6. a person or thing of no importance; nonentity

7. a design consisting of interwoven letters; monogram

8. music a defect in an organ resulting in the continuous sounding of a pipe, the key of which has not been depressed

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verb

1. to put (a message) into secret writing

2. (intr) (of an organ pipe) to sound without having the appropriate key depressed

3. rare to perform (a calculation) arithmetically

Other Word Forms

• cipherable
  adjective
• cipherer
  noun

Etymology

Origin of cipher

First recorded in 1350–1400; Middle English siphre, from Medieval Latin ciphra, from Arabic ṣifr “empty, zero”; translation of Sanskrit śūnyā “empty”

Explanation

A cipher is a secret code, usually one that's created using a mathematical algorithm. Sometimes the message written in code is itself called a cipher. Cipher comes from the Arabic sifr, which means "nothing" or "zero." The word came to Europe along with the Arabic numeral system. As early codes substituted numerals for letters to hide the word’s meaning, codes became known as ciphers. If you crack a cipher, you break the code and can understand the message. From its "zero" meaning, cipher can also be used for a person who has no influence or importance in the world.

Example Sentences

To make the journey work without the audiences seeing each other, Broucke used a mathematical application called a Caesar cipher, created by the Roman general to send encrypted messages.

From The Wall Street Journal • Apr. 2, 2026

But he has been a cipher when it comes to the administration’s military “excursions,” as Trump calls them, and has reportedly even been exiled from the makeshift Mar-a-Lago situation room.

From Salon • Mar. 16, 2026

The Cybertruck has become a cipher for this injustice.

From Slate • Jun. 22, 2025

While “Million Dollar Baby” is one of this year’s defining singles, Richman remains largely a cipher.

From New York Times • Dec. 6, 2024

Jemma’s cipher was so good, even Mr. Pinkerton would be impressed.

From "The Detective's Assistant" by Kate Hannigan

Related Words

• nonentity