What does code mean?
Code is a word with remarkable range: at its core it names any system of signs or rules used to stand in for something else. A spy's cipher is a code; so are Morse code, the genetic code, a nation's penal code, and the unwritten social conventions governing polite behaviour. Since the mid-twentieth century, its dominant sense has become the text of instructions programmers write in languages such as Python or C++, making 'code' one of the defining words of the digital age. Used as a verb, it means to convert a message into symbols or to write such instructions, with derivatives like encode, decode, coder, and coding extending its reach further. Whether describing secrecy, law, biology, or software, code always carries the idea of meaning compressed into a structured form that only those who know the system can fully interpret.
A system of words, symbols, or signals used to represent information, especially secretly or concisely; a set of laws or rules; program instructions in a programming language.
"The enemy never managed to crack our code."
Countable when referring to a specific system ('a code'); often uncountable when referring to software ('a lot of code').
To convert a message or information into a code or cipher; to write instructions for a computer in a programming language.
"The developers coded the entire feature over a single weekend."
'Code' as a verb is now more commonly associated with programming than with encryption, where 'encrypt' is preferred.
Plural refers to multiple distinct codes or rule systems; software source code is typically treated as uncountable.
"Building regulations require different fire codes in each state."
Every letter you type in a program is 'code' — but before computers existed, the word already meant secrets: it comes from codex, the ancient bound manuscript that replaced the scroll.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of code
Code entered English in the early seventeenth century from French code, which derived from Latin codex, originally meaning a tree trunk or wooden tablet and later a bound book of laws. The Latin codex itself may come from caudex, meaning trunk of a tree, reflecting the wooden tablets once used for writing. The modern computing sense arose in the twentieth century as programming developed, while cognates include English codex, codicil, and codify.
Related word forms
How code is actually used
In everyday speech, 'code' most often refers to software source code or identification systems like ZIP codes. In medical slang, 'to code' means a patient has gone into cardiac arrest, and a 'code blue' is an emergency announcement — register is informal/professional jargon.
Easily confused with code
A coda is a concluding passage of music or dance, whereas code is a system of symbols or rules.