bedgown vs nightgown

bedgown

noun
  • An article of women's clothing for the upper body, usually thigh-length and wrapping or tying in front; a bedjacket. 

  • A nightgown. 

nightgown

noun
  • A long loose robe worn mainly by women for sleeping in. 

  • A dressing gown. 

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