solemn vs tongue-in-cheek

solemn

adj
  • Deeply serious and sombre; grave. 

  • Characterized by or performed with appropriate or great ceremony or formality. 

  • Of or pertaining to religious ceremonies and rites; (generally) religious in nature; sacred. 

  • Inspiring serious feelings or thoughts; sombrely impressive. 

tongue-in-cheek

adj
  • Not intended seriously; jocular or humorous. 

adv
  • With irony. 

How often have the words solemn and tongue-in-cheek occurred in a corpus of books? (source: Google Ngram Viewer )