activity vs double date

activity

noun
  • Something done for pleasure or entertainment, especially one involving movement or an excursion. 

  • The lexical aspect (aktionsart) of verbs or predicates that change over time and have no natural end point. 

  • Something done as an action or a movement. 

  • The state or quality of being active; activeness. 

  • The number of radioactive decays per unit time. Unit for it: becquerel or curie 

  • The propery of substances to react with other substances 

double date

noun
  • A (romantic) date that two couples go on together. 

verb
  • To go on a double date. 

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