confession vs secret

confession

noun
  • The disclosure of one's sins to a priest for absolution. In the Roman Catholic Church, it is now also termed the sacrament of reconciliation. 

  • A formula in which the articles of faith are comprised; a creed to be assented to or signed, as a preliminary to admission to membership of a church; a confession of faith. 

  • The open admittance of having done something (especially something bad). 

  • A formal document providing such an admission. 

  • Acknowledgment of belief; profession of one's faith. 

secret

noun
  • Any prayer spoken inaudibly and not aloud; especially, one of the prayers in the Tridentine Mass, immediately following the "orate, fratres", said inaudibly by the celebrant. 

  • Private seclusion. 

  • A piece of knowledge that is hidden and intended to be kept hidden. 

  • The key or principle by which something is made clear; the knack. 

  • A form of steel skullcap. 

  • Something not understood or known. 

adj
  • Being or kept hidden. 

verb
  • To make or keep secret. 

  • To hide secretly. 

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