# cipher

Pronunciation: US say "SY-fer" /ˈsaɪfɚ/; UK say "SY-fuh" /ˈsaɪfə/

## Noun

1. A method or system for disguising a message by replacing or rearranging its letters or bits according to a set rule, so that only someone with the key can read it.
   - Simple: A secret way of changing the letters of a message so only certain people can read it.
   - _Email encryption tools often rely on a public-key cipher, so anyone can lock a message but only the recipient can open it._
   - _Researchers found a flaw in the cipher that let them recover the key in a few hours._
2. A message whose meaning has been concealed by a cipher; ciphertext.
   - Simple: A secret message written so that only some people can read it.
   - _The note on the back of the photograph was plainly a cipher, five-letter groups that meant nothing at first glance._
   - _Analysts worked through the intercepted ciphers one by one, hoping for a single careless repetition._
3. A person or thing of no importance.
   - Simple: A person or thing that does not matter at all.
   - _The board treated the new chairman as a mere cipher who signed whatever was put in front of him._
   - _With the founder running everything, the other directors were little more than ciphers._
5. A design formed by combining or interweaving letters, such as the initials of a name.
   - Simple: A design made by joining letters together, such as the first letters of a person's name.
   - _The silver cups were engraved with the family's cipher, an interlaced G and R._
   - _The old mailbox still carries the royal cipher of a long-dead king._
6. A hip-hop jam session. *(slang)*
   - Simple: A meeting where people play or rap hip-hop music together just for fun.
   - _After the show, a few of us jumped into a cipher in the parking lot and freestyled until security showed up._
   - _She held her own in the cipher, trading verses with rappers twice her age._
7. The route, usually a circle, that shared cannabis follows as it is passed around a group; also, a session of smoking cannabis. *(slang)*
   - Simple: The way shared cannabis is passed around a group, usually in a circle, or a time when people smoke it.
   - _Don't hold up the cipher, man. Puff and pass._
   - _A few friends lit up and started a cipher on the roof after work._

## Verb

4. To turn written messages into code or cipher.
   - Simple: To write in a secret code.
   - _Agents in the field were taught to cipher quickly, even by flashlight._
   - _He ciphered late into the night, turning each report into blocks of numbers._

## Noun

8. Zero, or the figure 0. *(dated)*
   - Simple: Zero, the number 0.
9. A numeral; any of the characters used in writing numbers. *(dated)*
   - Simple: One of the signs used to write numbers, such as 3 or 7.
10. A group of three digits within a number, especially one set off by commas or periods. *(obsolete)*
   - Simple: A set of three digits in a big number, often split off by commas or periods.
11. Any character used in writing a text, such as a letter or symbol. *(obsolete)*
   - Simple: Any letter, number, or other mark used in writing.

## Verb

12. To make calculations, working out sums with numbers. *(dated)*
   - Simple: To add, subtract, and do other math with numbers.
   - _Few of the farm children could cipher beyond simple addition._
   - _On the frontier, children learned to read, write, and cipher in a one-room schoolhouse._
13. To decipher: to make out the meaning of writing that is hard to read or of a coded message. *(obsolete)*
   - Simple: To work out what some writing or a secret message says.

## Other meanings

- (noun) A fault in an organ's action, whether in a valve, linkage, or wiring, that makes a pipe sound continuously without its key being pressed; also, the unwanted sound itself.
- (verb) Of an organ pipe, to keep sounding because of a fault, even though its key has not been pressed.

## Origin

English cipher comes from Middle English cifre, recorded in the 14th century. Middle English borrowed it from Old French cyfre or cyffre (modern French chiffre). The ultimate source is Arabic ṣifr ("zero, empty"), derived from ṣafara ("to be empty"). Cipher, chiffre, and zero are doublets.

Source: DictionaryAI, https://dictionaryai.com/define/cipher (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).