bollard vs gatepost

bollard

noun
  • A strong vertical post of timber or iron, fixed to the ground and/or on the deck of a ship, to which the ship's mooring lines etc are secured. 

  • A similar post preventing vehicle access to a pedestrian area, to delineate traffic lanes, or used for security purposes. 

gatepost

noun
  • a vertical post from which a gate is hung/attached. 

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