lawn-mower vs lawnmower

lawn-mower

noun
  • A lawnmower. 

lawnmower

noun
  • A person who landscapes and in particular mows lawns. 

  • A device used for cutting grass to a chosen height, typically of landscaped lawns of residences or institutions. 

  • A dance move in which the dancer mimics using a petrol lawn mower by pulling the starter cord and then pushing the mower forwards to the beat of the music. 

How often have the words lawn-mower and lawnmower occurred in a corpus of books? (source: Google Ngram Viewer )