brooding vs sincere

brooding

adj
  • Deeply or seriously thoughtful. 

  • Broody; incubating eggs by sitting on them. 

noun
  • A spell of brooding; the time when someone broods. 

sincere

adj
  • Meant truly or earnestly. 

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

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