What is the definition of meridiem?

Meridiem is a Latin word that means "midday" or "noon". It's often used in phrases like "ante meridiem" (AM) and "post meridiem" (PM), which indicate whether a time is before or after noon.

Here's a breakdown:

* Ante meridiem (AM): "Before midday" – refers to the period between midnight and noon.

* Post meridiem (PM): "After midday" – refers to the period between noon and midnight.

Therefore, "meridiem" itself doesn't refer to a specific time, but rather acts as a reference point for AM and PM.