a set of rules or principles or laws (especially written ones)
"The project team failed to launch because they violated the company's strict ethical code."
a coding system used for transmitting messages requiring brevity or secrecy
"The spy sent a quick text containing just two numbers, knowing they were part of an old code to communicate their location without alerting anyone."
(computer science) the symbolic arrangement of data or instructions in a computer program or the set of such instructions
"The developer spent all night debugging the code to fix the glitch that kept crashing the app."
A short symbol, often with little relation to the item it represents.
"The airline assigned us code YZ92 for our connecting flight, which had nothing to do with where we were actually going."
In plain English: A code is a special system of symbols or rules used to represent information so it can be understood only by those who know how to read it.
"The secret code for the safe was written on a sticky note."
Usage: Use "code" as a noun to refer to a system of symbols or signs used to convey information, such as traffic lights or Morse code. It specifically denotes a structured method where specific signals represent particular meanings rather than just any random symbol.
To write software programs.
"The doctor rushed into the room because the heart monitor beeped urgently that Mr. Miller had coded in his sleep."
Of a patient, to suffer a sudden medical emergency (a code blue) such as cardiac arrest.
In plain English: To code means to write instructions for a computer so it can perform specific tasks.
"The secret agents will code their message before sending it to the base."
Usage: In everyday usage, to code means to undergo a sudden medical emergency like cardiac arrest. Do not use this term for writing computer programs or secret messages; those are distinct meanings of the word "code."
The word "code" comes from the Latin cōdex, which originally referred to a wooden tablet used for writing before evolving to mean a book or legal system in English. While it entered Middle English as a term for law, its modern usage also includes phrases like "code blue," where the meaning is shortened from the full medical emergency designation.