aeroplane vs hot-air balloon

aeroplane

noun
  • Synonym of airplane. A powered heavier-than-air aircraft with fixed wings. 

  • Any of various nymphalid butterflies, of various genera, having a slow gliding flight. Also called planes. 

verb
  • To fly in an aeroplane. 

  • To transport by aeroplane. 

hot-air balloon

noun
  • A balloon-shaped aircraft whose bag is inflated with hot air; it carries passengers and crew in a gondola slung underneath. 

How often have the words aeroplane and hot-air balloon occurred in a corpus of books? (source: Google Ngram Viewer )