airship vs helicopter

airship

noun
  • A lighter-than-air aircraft that can be propelled forward through the air as well as steered. 

  • A police air unit, a police helicopter 

  • Any aircraft. 

  • A high ranking official of the RAF, viewed as arrogant and distant. 

verb
  • To transport goods by aircraft. 

helicopter

noun
  • An aircraft that is borne along by one or more sets of long rotating blades which allow it to hover, move in any direction including reverse, or land; and typically having a smaller set of blades on its tail that stabilize the aircraft. 

  • A powered troweling machine with spinning blades used to spread concrete. 

  • A whirling trick performed with devil sticks. 

  • A dragonfly. 

  • The winged fruit of certain trees, such as ash, elm, and maple. 

verb
  • To rotate like a helicopter blade. 

  • To overprotect one's children, as a helicopter parent does. 

  • To travel by helicopter. 

  • To transport by helicopter. 

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