day job vs profession

day job

noun
  • One's principal job; one's regular means of income. 

profession

noun
  • An occupation, trade, craft, or activity in which one has a professed expertise in a particular area; a job, especially one requiring a high level of skill or training. 

  • The practitioners of such an occupation collectively. 

  • The declaration of belief in the principles of a religion; hence, one's faith or religion. 

  • A promise or vow made on entering a religious order. 

  • Any declaration of belief, faith or one's opinion, whether genuine or (as now often implied) pretended. 

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