carding machine vs flashcard

carding machine

noun
  • A machine used for carding materials. 

flashcard

noun
  • A card used to aid rote memorization. One side of the card contains data of one kind, or a question, and the other side contains the associated response which one wants to memorize. For example, one side could contain an English word, and the other side the Spanish translation. 

  • A solid-state digital memory storage format, commonly found on computers, digital cameras and cellphones. 

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