Speaking of Which – Meaning & Formal Synonyms

You might have noticed that, while you hear “speaking of which” quite a lot in spoken conversations, you don’t encounter it much in books.

What does this phrase mean, and is it okay to use it? Read on to find out.

What Does “Speaking of Which” Mean?

You can use the phrase “speaking of which” to introduce a new idea that is in some way linked to a current or previous topic of conversation, e.g., “I’ll have to pick your sister up later. Oh, speaking of which, can you babysit her this weekend?”

speaking of which meaning


  • You can use “speaking of which” to introduce a new idea that is in some way related to a current or former topic of conversation.
  • While you can use “speaking of which” in verbal conversations, you should avoid using it in text.
  • Some alternative phrases are “by the way”, “incidentally”, and “on a related note”.

Although native English speakers often pop this phrase into their casual conversations, you are unlikely to find it in writing. That’s because this construction is not formally accepted in English, even though English speakers use it verbally all the time!

As such, you should avoid using this phrase, even in informal writing.

Keep this in mind as we look at how to use “speaking of which” in a sentence. Try to imagine these sentences being said out loud, as this is where you are most likely to hear this phrase:

  • Person 1: I didn’t get a wink of sleep last night. I kept seeing this ominous figure floating in the corner of the room in my periphery.
  • Person 2: Speaking of which, did you hide my new dressing gown under the bed?
  • Person 1: I like Batman, but I just think he’s a little outdated as a concept.
  • Person 2: I completely agree. Speaking of which, did you ever read any Midnighter comics? He’s way more suited for 2022 than the Bat.

What to Say Instead of “Speaking of Which”

Other ways to say “speaking of which” are “by the way”, “incidentally”, and “on a related note”. Some of these can be used as formal synonyms for “speaking of which”. Happily, unlike “speaking of which”, you can use these alternatives in writing.

1. By The Way

According to the Cambridge Dictionary, “by the way” is “used to introduce a new subject to be considered or to give further information”.

As you can tell from this definition, “by the way” is not an exact synonym for “speaking of which”. You can use it to introduce a new subject that might be unrelated to the previous topic, whereas you would only use “speaking of which” to introduce a topic relating to the conversation already being had.

Let’s see how we can use “by the way” in a manner similar to “speaking of which”:

  • Person 1: Steve’s been looking quite pallid lately. Do you think he’s eating enough?
  • Person 2: I don’t know, I don’t look at him much. By the way, what does “pallid” mean?
  • Person 1: I’m supposed to be meeting the boss at noon. By the way, what time is it?
  • Person 2: I’m not sure you want to know the answer to that.

2. Incidentally

Another synonym for “speaking of which” is “incidentally”. This phrase adds new, related, yet potentially less important information to a conversation. In this way, you can use it in a similar way to the former phrase.

Let’s look at a few examples that illustrate this:

  • Person 1: We had a great time house sitting for Mr. Teach. Incidentally, he has a cat named Loki, just like you!
  • Person 2: “Incidental” my left foot – he’s a name thief, I’d say!
  • Person 1: Look at this dress I bought! Thought I’d treat myself after a long, hard day of browsing online stores.
  • Person 2: Incidentally, Lucius, I wanted to talk to you about your credit card debts.

3. On A Related Note

Another way to say “speaking of which” is “on a related note”. In this expression “note” does not refer to written notes or musical notes per se, but generally refers to the topic being discussed.

A tad wordier than our other examples, you can use this phrase in more formal circumstances, such as business meetings.

Let’s look at an example to illustrate this:

  • Person 1: Our firm is a business, so we’ve ensured that our applications test the business and commercial awareness of our candidates.
  • Person 2: That’s fantastic. On a related note, I wonder if it would be a good idea to include some business subjects in the legal degree if graduates are expected to have business knowledge?
  • Person 1: Don’t be ridiculous.

4. With Regard To

According to the Macmillan Dictionary, “with regard to” essentially means “concerning a particular subject”.

You can use this phrase in a similar way to “speaking of which”, in that it can introduce a new idea based on something already said. It does differ slightly from “speaking of which”, however, since it can refer back to far earlier conversations.

Let’s see some examples of this phrase in action:

  • With regard to what Mr. Peters said earlier, I see no reason why business subjects couldn’t be incorporated into a law degree.
  • With regard to the name of Mr. Teach’s cat; do you think he’d be willing to change it?

5. While We’re On The Subject

“While we’re on the subject” is a wordier way to say “speaking of which”. It introduces a new idea while making clear that it is related or linked to the topic currently being discussed.

Consider these examples

  • Person 1: I just haven’t a clue how I’m going to get myself out of all this debt.
  • Person 2: While we’re on the subject, my gran says you still owe her for that bingo fiasco the other night.
  • While we’re on the subject of 80’s fashion, I actually keep a crop top in my car at all times, just in case.