What is a compound word for after mid day?

There isn't a single, widely accepted compound word for "after midday." However, here are some options depending on the specific nuance you're trying to convey:

Formal:

* Afternoon - This is the most common and straightforward term.

* Post-meridian - This is a more technical term, literally meaning "after midday."

Informal:

* Late afternoon - This emphasizes the time being later than midday.

* Early evening - This emphasizes the time being closer to evening.

Literary:

* Eventide - This has a poetic feel and refers to the time of day when the sun begins to set.

The best choice will depend on the context of your writing.