in straight line vs linear

in straight line

linear

adj
  • A type of length measurement involving only one spatial dimension (as opposed to area or volume). 

  • Long and narrow, with nearly parallel sides. 

  • Made, or designed to be used, in a step-by-step, sequential manner. 

  • Of or relating to a class of polynomial of the form y=ax+b. 

  • Of or relating to lines. 

  • Having the form of a line; straight or roughly straight; following a direct course. 

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