day vs time of day

day

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

  • 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. 

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

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

time of day

noun
  • A loosely specified period of time, minutes or hours in duration, especially daytime, or point in time. 

  • The time according to the clock. 

  • The greeting appropriate to the time of day. 

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