swimming costume vs swimsuit

swimming costume

noun
  • the garments that one wears when bathing in the sea or a swimming pool, especially the one-piece garment worn by women and girls. 

swimsuit

noun
  • A garment worn for swimming. 

  • A tight-fitting one-piece garment worn by women and girls. 

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