I need help finding a good word for the point in time where one day switches to the next. Obviously, the actual point in time would be midnight, but I want a word to emphasize the fact that something is happening over the switching point between two days. So the word I'm looking for would be something like "day limit" or "daybreak", but neither of these sounds very good.
If any kind of digital clock or calendar is in the picture, then rollover can describe this.
It needs a little context to make it clear: e.g. something like “Nominations open Saturday February 21, at the rollover” may not be understood by all readers, but “Nominations open at midnight, on the rollover from Fri 20 to Sat 21” should be well understood, as should “Nominations open Friday night, at the rollover from 11:59 to 12:00”.
I think that at the stroke of midnight is a useful expression that comes close to what you are looking for. It actually indicates the last moments of the day and the beginning of a new one.
- the sound of striking, as of a clock
You might try this :
On the cusp of a new day.
- On the threshold or verge of a development or action. (TFD)
Using some Latin, you might consider interdiurnum to be that instant that is between successive days (like interregnum is the time between successive reigns or regimes).
inter (Etymmonline) is
among, between, betwixt, in the midst of
of the day.
This purposefully overlooks the idea that for some cultures the day ends and begins at midnight, for other cultures the day ends and beings at sunset, or any other concept of when that instant might occur.
Perhaps changing of the day would work if you need a noun. As the new day began... would also work and would perhaps sound a little less awkward if a prepositional lead-in phrase will work for you.
Both of these indicate the transitioning to the new day rather than just denoting a particular instant.
A poetic offering,
the Hollow (or, hollowed) Hour, that interstice between the past and the future
- having a hole or empty space inside.
The Hollow Hour = 00:00:00 and connotes the emptiness out of which all manifestation proceeds. "Hollowed" echoes, yet opposes, the concept of that which is "hallowed". This interstice in space or time is where all go to die; from where all are born anew. "This is where the world ends"; This is where it all begins again.
A small opening or space between objects
An interval of time required by the Roman Catholic Church between the attainment of different degrees of an order.
(by extension) A small interval of time free to be spent on activities other than one's primary goal.
(figuratively) A fragment of space.