nocturnal vs twilight

nocturnal

noun
  • A device for telling the time at night, rather like a sundial but read according to the stars. 

  • A person or creature that is active at night. 

adj
  • Taking place at night, nightly. 

  • Primarily active during the night. 

twilight

noun
  • The time when this light is visible; the period between daylight and darkness. 

  • Any faint light through which something is seen; an in-between or fading condition. 

  • The soft light in the sky seen before the rising and (especially) after the setting of the sun, occasioned by the illumination of the earth’s atmosphere by the direct rays of the sun and their reflection on the earth. 

  • The time when the sun is less than 18° below the horizon. 

adj
  • Pertaining to or resembling twilight; faintly illuminated; obscure. 

verb
  • To illuminate faintly. 

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