caution vs flashcard

caution

noun
  • A yellow card. 

  • A formal warning given as an alternative to prosecution in minor cases. 

  • Security; guaranty; bail. 

  • Prudence when faced with, or when expecting to face, danger; care taken in order to avoid risk or harm. 

  • A careful attention to the probable effects of an act, in order that failure or harm may be avoided. 

verb
  • To warn; to alert, advise that caution is warranted. 

  • To give a yellow card 

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 caution and flashcard occurred in a corpus of books? (source: Google Ngram Viewer )