sincere vs true-hearted

sincere

adj
  • Genuine; meaning what one says or does; heartfelt. 

  • Meant truly or earnestly. 

true-hearted

adj
  • Having a faithful heart; honest; sincere; not faithless or deceitful. 

How often have the words sincere and true-hearted occurred in a corpus of books? (source: Google Ngram Viewer )