costume vs kirtle

costume

noun
  • An outfit or a disguise worn as fancy dress etc. 

  • A style of dress, including garments, accessories and hairstyle, especially as characteristic of a particular country, period or people. 

  • A set of clothes appropriate for a particular occasion or season. 

verb
  • To dress or adorn with a costume or appropriate garb. 

kirtle

noun
  • A woman's gown; a woman's outer petticoat or skirt. 

  • A knee-length tunic. 

  • A short jacket. 

verb
  • To clothe or cover with, or as if with, a kirtle; to hitch up (a long garment) to the length of a kirtle. 

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