garment vs underskirt

garment

noun
  • A single item of clothing. 

  • The visible exterior in which a thing is invested or embodied. 

verb
  • To clothe in a garment. 

underskirt

noun
  • A skirt worn underneath another skirt; a petticoat. 

  • An under layer of a multi-layer gown over which outer skirts are draped. 

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