picnic vs round up

picnic

verb
  • To take part in a picnic. 

noun
  • An easy or pleasant task. 

  • An informal social gathering, usually in a natural outdoor setting, to which the participants bring their own food and drink. 

  • The meal eaten at such a gathering. 

  • A cut of pork from the shoulder area (above the front leg) of a pig. 

round up

verb
  • To collect or gather (something) together. 

  • To gather (cattle) together by riding around them. 

  • To round (a number) to the smallest integer that is not less than it, or to some other greater value, especially a whole number of hundreds, thousands, etc. 

  • To arrest or detain a group of people without individualized suspicion or cause, often as a form of targeted persecution. 

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