day vs solar day

day

noun
  • Rotational period of a planet (especially Earth). 

  • Any period of 24 hours. 

  • The part of a day period which one spends at one’s job, school, etc. 

  • A period from midnight to the following midnight. 

  • A period of contention of a day or less. 

  • A 24-hour period beginning at 6am or sunrise. 

  • A specified time or period; time, considered with reference to the existence or prominence of a person or thing; age; time. 

  • Part of a day period between sunrise and sunset where one enjoys daylight; daytime. 

verb
  • To spend a day (in a place). 

solar day

noun
  • one day of solar time, the time between successive noons; the time in which a planet such as Earth apparently rotates once around its axis, relative to the sun (on Earth about 24 hours as an average - the length of solar day is not constant throughout the year) 

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