How long does it take to mull something over?

I used the phrase "we'll mull it over" in an e-mail. My intent was to let the readers know that we (the team) needed to give it due consideration and come up with a considered response to their obviously important question. To my mind, we clearly needed to think things over, but for how long? I meant overnight (though didn't say so), but my audience assumed we would take a week.

What period of time (if any) does the use of the word mull convey?

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Indeterminate, just as when you say "Let me meditate on it" or "Let me think about it and I'll get back to you". Mull implies its not going to be a quick response, so it could be a while, or even a "fortnight", depending on how complicated the situation. – FrankComputerAtYmailDotCom Sep 25 '12 at 3:58
Here are plenty of written instances of "mulled it over for a few seconds". It's about as meaningful as "How long is a piece of string?" - in short, Not Constructive. – FumbleFingers Sep 25 '12 at 17:40

Mulling takes an indeterminate time. If you're mulling wine, you heat gently, and add spices; it might take twenty minutes. If you're mulling over a life-changing decision, you might take several weeks, possibly longer. Anywhere in between might be counted as mulling.

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In mulling wine, mulling means something different from I am mulling over a life-changing decision. – kiamlaluno Feb 9 '11 at 7:58
I'm sure Jonathan knows the difference, the point is no less valid, and I think this is a colourful way of making it. – Ed Guiness Feb 9 '11 at 9:52
@kiamlaluno: +1! I was about to comment to disagree with you, since I’d always thought that “mull over” was a figurative usage, derived from what you do when mulling wine. But going to the OED to get a source, I find I was completely wrong — it seems they’re quite possible not etymologically connected at all, though nobody’s quite sure where mulling wine does come from! – PLL Feb 9 '11 at 10:04
@Ed Guiness: For how mulling wine is used nowadays, there is no reference to time; you could take 2 minutes or 20 minutes to get mulled wine. – kiamlaluno Feb 9 '11 at 10:24
@kiamlaluno Indeed, making it a metaphor. – Ed Guiness Feb 9 '11 at 10:31

I don't believe that the word mulling in your context has any period of time associated with it. It refers to the act of thinking something over or considering something in one's own mind or as a group. Your audience may have assumed a week for a response simply because they estimated it would take that long. If their question was indeed important you may have been better off giving them an explicit timing for your response: "...we'll mull it over and give you an answer tomorrow."

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Mulling something over is vague time-wise; you can safely assume a week, and probably longer.

The phrase is troublesome not just because it is vague, but also doesn't convey a sense of serious consideration; it sounds half-hearted. It's best to avoid it in a business e-mail.

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too right. I was actually busy fire-fighting completely different issues and probably stuck the word mull in there because I knew I wasn't giving it immediate attention. – ukayer Feb 9 '11 at 8:55
I’m interested you say it sounds half-hearted to you. To me, mull over has quite the opposite connotations: I think of it as meaning to give something time, to consider it seriously. (The OED roughly agrees: “to turn over (an idea, etc.) in one's mind; reflect upon, think over, ponder.”) – PLL Feb 9 '11 at 10:09
You could say something like "Let's mull it over for a day or two" to add a bit more clarity concerning the time to be taken. – RedGrittyBrick Feb 9 '11 at 10:18
I'd agree with PLL that mulling is not half-hearted; it's simply not knee-jerking. Taking time (as much time as is necessary) to consider the issue before coming to a conclusion. Arguably more 'serious' than a quick, instinctive decision. – CJM Feb 9 '11 at 12:13
Good point, PLL. mickeyf's answer expressed it better. – The English Chicken Feb 9 '11 at 17:14

In this particular case, it could very well have meant "We have no intention of getting back to you EVER, but we're not going to come out and say that, we're going to leave you hanging."

It is the fact that it is so vague that allows it to be used this way. In business or other negotiation/communication, being anything less than definitive frequently means either saying "No" or revealing your own lack of understanding.

If you meant "a week" it would have been courteous, more informative, and an indication of sincerity to have said "we'll mull it over and get back to you in a week".

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To mull, in the context given from the question, means think about (a fact, proposal, or request) deeply and at length. The word is a little vague on how much time thinking will take.

Instead of mull you can use ponder, consider, think over, think about, reflect on, or give some thought to.

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To expect your mail recipient to consult a dictionary for the literal meaning of to mull would be stretching it a bit too far. The impression it gives is one of casual dismissal, which is not appropriate in business communications.

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I always thought the word mull was associated with the Old English word fortnight (two weeks).

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'Fortnight' is a contraction of 'fourteen nights'; in Jane Austen (Pride & Prejudice, Chapter 13, Mr Collins letter), you come across "se'ennight" for 'seven nights' or 'week'. 'Fortnight' is not only Old English; it is still used frequently in England (but "se'ennight" is obsolete). I've never heard of "Mull" in the context of 'fortnight', but that may be just not having listened to the right information. – Jonathan Leffler Sep 25 '12 at 2:59
Interesting!.. Back in 1988, I heard an English friend of mine say "Let me mull it over a fortnight". I understood the word "mull" but did not know back then what "fortnight" meant and asked him. – FrankComputerAtYmailDotCom Sep 25 '12 at 3:06