/rɪˈplaɪ/
[verb] To say, write, or do something in response to what someone else has said, written, or done. It can also be used as a noun to mean the response itself.
'Reply' literally meant 'to fold back' — as if your answer were a piece of paper being returned to its sender.
The word 'reply' traces its roots to the Latin verb 'replicare', which was built from two parts: 're-', meaning 'back' or 'again', and 'plicare', meaning 'to fold'. The original, very physical image was of folding something back on itself — like turning a piece of cloth or papyrus back the way it came. This same root 'plicare' gave the world a rich family of English words: Latin plicare → Old French plier → English 'ply', and Latin replicare → Old French replier → Middle English 'replien', which eventually became 'reply'.
In Classical Latin, 'replicare' carried the sense of unrolling or unfolding something, and also of going back over an argument — revisiting a point in a debate or legal dispute. Roman lawyers and orators used the word to describe responding to a charge or a line of reasoning. This legal flavour gave the word an early air of formality and deliberate counter-speech, quite different from the casual back-and-forth we associate with a reply today.
The word entered Middle English in the 14th century, arriving through Old French 'replier', which had already softened the meaning from the physical act of folding to the more abstract act of responding. At first, English writers used 'replien' mainly in formal and legal contexts, echoing the Latin tradition. Gradually, over the 15th and 16th centuries, it broadened into everyday use, becoming a simple, versatile word for any kind of answer.
What is especially interesting is how the 'folding' metaphor quietly survived in the language. Think of the word 'reply' as a letter being folded and sent back to you — the same piece of communication, returned. This image connects 'reply' to a surprising number of familiar English words. Latin plicare → English 'implicate' (to fold someone into something), Latin plicare → Old French complier → English 'comply' (to fold oneself to another's will), and Latin replicare → English 'replicate' (to fold again, to copy exactly). All of these share that original idea of folding.
By the time of Shakespeare, 'reply' was fully at home in English at every level of society, from courtroom to kitchen. It had completely shed its physical meaning and existed purely in the world of language and communication. The noun form — 'a reply' — developed naturally alongside the verb, just as 'a supply' grew from 'to supply'. Over the centuries that followed, the word remained remarkably stable, keeping its form and meaning almost unchanged through to the present day, where it has found a second life in the digital age — in email threads, social media, and messaging apps — as one of the most frequently clicked words on a screen.