meridiem

Yeah you're not wrong, but AM is ante meridiem and PM is post meridiem where meridiem is mid day.

Midnight is not AM nor PM because it's neither ante meridiem nor post meridiem.

So you say ante meridiem and post meridiem.

The terms are from the Latin ante meridiem and post meridiem (meridiem, midday, ante before, post after) so it seemed logical to me that any Romance language would have them.

Reading this I learnt that '12:00 PM' is noon in America, and not literally 12 hours post meridiem, i.e.

It's usually held to be Latin: ante and post meridiem[1].

Noon is the meridiem that AM and PM reference.

= post meridiem, etc.), so probably in some of the other Romance languages they do match?

Instantaneously it becomes post-meridiem.

:D Maybe it's just me, but compared to other timepickers you don't have multiple buttons for each element(hours, minute, meridiem), which gives you a simpler design, that can look similar to your datepicker.

As soon as the moment has been observed it has passed, and you are now "post meridiem".

The word "meridiem" means "noon", the middle of the day.

While your ordinary clock will show 12:00pm at midday for a full minute, your high precision clock might be showing 12:00:00.0000001 -- indisputably "post meridiem".

It's technically correct, since am=ante meridiem="before noon".

At this point markwhen is available as a VS Code extension, Obsidian plugin, CLI tool, and web editor in Meridiem.

Meridiem seems to only have ARM builds, no Intel builds.

Especially in the afternoon (Post Meridiem).