airlift vs helicopter

airlift

verb
  • To transport (troops etc) in an airlift. 

noun
  • The transportation of troops, civilians or supplies by air, especially in an emergency. 

  • Such a flight. 

  • A pipe that is used to suck up objects from the sea bed. 

helicopter

verb
  • To transport by helicopter. 

  • To rotate like a helicopter blade. 

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

  • To travel by helicopter. 

noun
  • 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. 

  • 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. 

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