informal vs low-pressure

informal

adj
  • Reflecting everyday, non-ceremonious usage. 

  • Suited for everyday use. 

  • Not in accord with the usual regulations. 

  • Not formal or ceremonious. 

  • Not organized; not structured or planned. 

low-pressure

adj
  • The opposite of high-pressure, defined by contrast. 

How often have the words informal and low-pressure occurred in a corpus of books? (source: Google Ngram Viewer )