Crepuscule and Vespers

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

Vespers and crepuscule are semantically related. in beginning of darkness topic. In some cases you can use "Vespers" instead a noun "Crepuscule".

Vespers noun - The sixth of the seven canonical hours of the divine office; early evening; now often made a public service on Sundays.

Crepuscule and vespers are semantically related. You can use "Crepuscule" instead a noun "Vespers".