Today one of my students asked me what “re:” stood for in the subject lines of e-mails (and letters). I thought I’d write the answer here, too, since many people take it to mean something else.
“Re:” is what is written in the subject line of e-mails (and in letters) to tell the receiver what the topic of the message is. For example: ‘Re: Your article’. Most people take this “re:” to stand for ‘reference’ or ‘regarding’. The reason for this could be that both these words start with the letters ‘re’, and what follows these letters is actually referring to the topic of the message. However, this is a misconception. What “re” actually stands for is the Latin word “res”. “Re” is the ablative form of the noun “res”, which means ‘thing’ or ‘affair’. Therefore, “re” means ‘about the thing’ or ‘about the affair’.