Sister vs devotional

Sister

noun
  • Title of respect for an adult female member of a fraternal/sororal organization, or comrade in a movement, or even a stranger using fictive kin. 

  • A title used to personify or respectfully refer to concepts or animals. 

  • Title of respect for an adult female member of a religious order. 

devotional

noun
  • A brief religious service. 

  • A text or piece of music or writing to be used for devotion. 

adj
  • Of or pertaining to devotion or worship. 

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