sincere vs truth-telling

sincere

adj

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

  • Meant truly or earnestly. 

truth-telling

adj

  • Telling the truth; honest, frank. 

noun

  • The act of telling the truth. 

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