Given that...

  1. If Jeremy is a "parent" to Sarah, then Sarah is a "child" to Jeremy.
  2. If archaeopteryx is an "ancestor" to chicken, then chicken is a "descendent" of achaeopteryx.

It seems to me that if a letter is written in response to another, then there is a similar two-way relationship between those two letters, but I'm a bit stuck on coming up with a good word to describe that relationship. Perhaps:

  1. If B is a "reply" to A, then A is an "antecedent" to B.
  2. If B is a "reply" to A, then A is a "precursor" to B.

But I'm not particularly fond of either. Is anybody aware of a term that has been used within the context of such communications?

Note - I have re-worded the above considerably, as it seems that a number of answerers were under the impression that I was looking for correct phrasing to write in a reply, such as "in response to your letter dated..." Hopefully the re-phrasing of the question might help avoid any more folks putting effort into such answers. My apologies if my intent wasn't clear enough previously.

  • This request needs more context. Could you provide the full sentence(s) that you are trying to create? I think there's probably a better way to phrase it entirely.
    – andi
    May 14, 2014 at 15:30
  • To be honest, it's a bit more hypothetical than that. It's just something I got to thinking about when trying to describe relationships between letters, telegrams, emails, etc. For instance, if B is a "reply" to A, then A is a "???" to B.
    – Steve
    May 14, 2014 at 15:56
  • If you're looking for something in common usage, there is no such word.
    – andi
    May 14, 2014 at 16:41
  • Archaically, if B is a reply to A, then A was plied to B. May 14, 2014 at 18:29
  • In internet slang, A is the "OP" letter.
    – JeffSahol
    May 14, 2014 at 20:32

4 Answers 4


After introducing the letter you are responding to (your letter d.d. April 5th), you can refer to it later simply as your letter - unless there are more letters from the same sender that you address in the same response, then you will need a more elaborate reference at every mention.

But if you refer to the same letter throughout your response, it works fine:

As you have stated in your latter, it is of great concern ...
Furthermore, when your letter addresses the increasing need to...
But sadly I found no mention in your letter as to the implications of...

  • Or your correspondence if you want to sound more legal. May 14, 2014 at 17:35
  • "Your last" is also sometimes used to refer to the letter you are responding to.
    – chapka
    May 14, 2014 at 18:05

I don't think that a single word can cover all situations involving the antecedent of a reply. In part, this is due to the nature of written correspondence, as opposed to, say, biological lineage. Whereas in the line from archaeopteryx to chicken (assuming that it's direct), every descendent in the direct line is also an ancestor of the chicken, and the chicken is the descendent of every intervening creature in that direct line, a series of letters or messages and replies lacks any such predictability.

Given the series

Message 1, Reply 1, Message 2, Reply 2, Message 3, Reply 3, Message 4, Reply 4, ...

it is highly unlikely that each reply in the series is a reply not just to the immediately preceding message but to all of the preceding messages.

Even in a particular line of human descent, each parent is linked to a single child, who in turn becomes parent of a single child in that line. Each parent/child in the series has a one-to-one relationship with one other parent and one other child in the line.

In contrast, it's possible for any reply (after the first) in a line of correspondence to be not a response to the immediately preceding message, but a generation-skipping second attempt to answer an earlier question, or a followup to a previous reply in the string of messages, or a message only tangentially related to any of the preceding messages, or an attempt to address remaining issues from multiple previous messages.

What this means is that any word corresponding to reply would have to comprehend such disparate possible meanings as "original message," "second message," "third message," "most recent message," "message of [date]," "one among two or more previous message jointly answered," and "followup to my own reply #n," Under the circumstances, we're better off using multiple words to specify which option we have in mind than trying to come up with a blanket term for all situations.

A second consideration here is that (at least in English) initiating actions aren't especially often defined on the basis of their relation to their consequence. Admittedly some examples do exist:

  1. If B is the effect of A, then A is the cause of B.

  2. If B is a response to A, then A is a stimulus to B.

But far more often (I suspect), our language doesn't go out of its way to establish such reciprocity. Consider these counterexamples:

  1. If B is a reaction to A, then A is a what to B?

  2. If B is a punishment for A, then A is a what for B?

  3. If B is a subject [in the nongovernmental sense] of A, then A is a what of B?

In everyday English, we use many single words to identify results, consequences, or focuses of other things (such as "reaction" as a result of "action," "punishment" as a consequences of "crime," and "subject" as a focus of "study"), but we are somewhat less likely to dedicate single words to identifying a prompt in terms of the response it elicits.

  • A very clearly explained analysis. :-)
    – Erik Kowal
    May 14, 2014 at 20:29
  • 1
    Now I'm curious about whether any other languages do have more tendency to define reciprocal relationships between actions and consequences. Although I guess that's off-topic around here. :)
    – Steve
    May 15, 2014 at 8:41

You can say: with reference to your latest letter or your last letter depending on the frequency of writing.


Consider cause.

cause: a person or thing that acts, happens, or exists in such a way that some specific thing happens as a result.

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