dusk vs early morning

dusk

noun
  • A period of time at the end of day when the sun is below the horizon but before the full onset of night, especially the darker part of twilight. 

  • A darkish colour. 

  • The condition of being dusky; duskiness 

adj
  • Tending to darkness or blackness; moderately dark or black; dusky. 

verb
  • To begin to lose light or whiteness; to grow dusk. 

  • To make dusk. 

early morning

noun
  • the time between midnight and sunrise 

How often have the words dusk and early morning occurred in a corpus of books? (source: Google Ngram Viewer )