doggie bag
noun
dog·gie bag ˈdȯ-gē- 
variants or doggy bag
: a container for leftover food to be carried home from a meal eaten at a restaurant
Example Sentences
Recent Examples on the Web But be prepared to leave uneaten pieces onboard, as these goodies are made for in-flight enjoyment only—no doggie bags allowed. 
Cynthia Drescher, Condé Nast Traveler, 10 July 2018 In 2016, the government required restaurants that serve more than 150 customers a day to provide doggie bags if requested. Elena Berton, USA TODAY, 2 May 2018 This also denies me the pleasure of a doggie bag to take home for another meal. Carolyn Hax, The Seattle Times, 6 Sep. 2017
Cynthia Drescher, Condé Nast Traveler, 10 July 2018 In 2016, the government required restaurants that serve more than 150 customers a day to provide doggie bags if requested. Elena Berton, USA TODAY, 2 May 2018 This also denies me the pleasure of a doggie bag to take home for another meal. Carolyn Hax, The Seattle Times, 6 Sep. 2017 Word History
Etymology
doggy entry 1; from the presumption that such leftovers are intended for a pet dog
First Known Use
1957, in the meaning defined above