How to avoid ambiguity when referring to a 24-hour period?

Question

Suppose I want to refer to a 24-hour period (from midnight till midnight). The word "day" can in fact mean "24 hours" (as in here), however it's somewhat ambiguous. I believe that if I say something like "just wait a day", most people will understand it in a common meaning. I could also say "just wait 24 hours", but that sounds a little weird to me, about as much as saying "I want 127.5 grams of cheese, please" in a store.

So how would a native speaker refer to the 24-hour period to avoid ambiguity (and being concise in the same time)? Maybe there is a fancy scientific word for it?

Answer 1

There's nothing weird about saying 24 hours, but if you want to avoid it you can say until / at / by this time tomorrow.

Answer 2

First off, make up your mind if you are looking at day or 24 hours — they are not quite the same thing! The first, Nychthemeron, is I feel not very relevant here.

Rather, the OP means a period of 24 hours from a reference point.

Considering this, (and in order not to sound weird), I'd actually just say, "Same time, tomorrow."

Answer 3

It depends on how exact you need to be.

• If you mean precisely 24 hours (for instance, for business purposes - some banks freeze funds for exactly 24 or 48 hours after a deposit), saying "24 hours from now" is fine. It also works with 48 hours and occasionally 72, but after that you're getting unwieldy and you're better off just saying "next Tuesday at 3:57."
• If you're a little looser in your requirements (i.e. asking a friend to meet you at around 2pm tomorrow when it's 2pm today, but not assuming that he'll be there on time to the second), then something along the lines of Kris's answer is best.
• If you're being any vaguer than that, just go with "tomorrow."

Answer 4

Nychthemeron - n. The natural day and night, or space of twenty-four hours.
Webster's Revised Unabridged Dictionary, published 1913 by C. & G. Merriam Co.

Answer 5

There isn't a specific word for this in English that is in common use; nychthemeron is not such a word. People will typically refer instead to "24 hours" or "[the] 24-hour period" ["between X and Y" or "from X to Y"].

Answer 6

Diel and circadian are additional adjectives to consider, when in a scientific context.

diel:

involving a 24-hour period that usually includes a day and the adjoining night · diel fluctuations in temperature

(Merriam-Webster)

circadian:

adj. Biology Relating to or exhibiting approximately 24-hour periodicity.

(American Heritage Dictionary)

Answer 7

Civil day -- midnight to midnight. It's even got legal precedent!

Solar day aka mean solar day aka astronomical day -- noon to noon. I suspect this is the fancy scientific term you had maybe heard of and your subconscious is trying to get you to remember. (The opposite-sounding sidereal day is not, however, what you would think.)