ambiance vs terrain

ambiance

noun
  • A particular mood or atmosphere of an environment or surrounding influence. 

  • A secondary color of a polygon that becomes more pronounced with shading. 

terrain

noun
  • An area of land or the particular features of it. 

  • The surface of the earth; the ground. 

  • A single, distinctive rock formation; an area having a preponderance of a particular rock or group of rocks. 

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