Eventide and Early black

Eventide noun - The time from when the sun begins to set to the onset of total darkness.

Early black and eventide are semantically related In some cases you can use "Early black" instead a noun "Eventide".

Eventide and early black are semantically related in evening topic. You can use "Eventide" instead a noun phrase "Early black", if it concerns topics such as latter part of a day.