Picnic

Picnic was barrowed from hte French piquenique, a word which seemed to originated around the end of the 17th Century. It is not clear where it came from. Orriginally the word picnic denoted a sort of party to which everyone brought along some food: the notion of an "outdoor meal" did not emerge untill the 19th century.

Source: Dictionary of Word Origins, John Ayto