astern vs dorsal

astern

adv
  • Behind (a vessel); in the rear. 

  • In the direction of the stern; backward (motion); to the rear. 

adj
  • Behind a vessel; having a bearing of 180 degrees from ahead. 

dorsal

adj
  • Relating to the surface naturally inferior, as of a leaf. 

  • Relating to the surface naturally superior, as of a creeping hepatic moss. 

  • Having only one sharp side. 

  • Relating to the top surface of the foot or hand. 

  • Produced using the dorsum of the tongue. 

noun
  • A hanging, usually of rich stuff, at the back of a throne, altar, etc. 

  • A sound produced using the dorsum of the tongue. 

  • Any of the longitudinal series of plates that encircle the body, excluding the ventral scales. 

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