at ease vs placid

at ease

prep
  • Allowed to refrain from being in rigid formation. 

  • Free of anxiety; not stressed or tense. 

  • In a relaxed position with the feet apart rather than at attention. 

placid

adj
  • calm and quiet; peaceful; tranquil 

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