abaxial vs excentric

abaxial

adj
  • Of a side that is facing away from the axis or central line, such as the underside of a leaf; or the back of an animal. 

  • Not in the axis. Applied to an embryo placed out of the axis of the seed. 

excentric

adj
  • One-sided; having the normally central portion not in the true center. 

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