moping vs sullen

moping

noun
  • The act of one who mopes. 

sullen

noun
  • Sullen feelings or manners; sulks; moroseness. 

adj
  • Having a brooding ill temper; sulky. 

  • Gloomy; dismal; foreboding. 

  • Sluggish; slow. 

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