A slacker is a person who habitually avoids work or lacks work ethic.
According to different sources, the term slacker dates back to about 1790 or 1898. It gained some recognition during the British Gezira Scheme in the early to mid 20th century, when Sudanese labourers protested their relative powerlessness by working lethargically, a form of protest known as "slacking".
In the United States during World War I, the word "slacker" was commonly used to describe someone who was not participating in the war effort, especially someone who avoided military service, an equivalent of the later term draft dodger. Attempts to track down such evaders were called slacker raids. During World War I, U.S. Senator Miles Poindexter discussed whether inquiries "to separate the cowards and the slackers from those who had not violated the draft" had been managed properly. A San Francisco Chronicle headline on September 7, 1918, read: "Slacker is Doused in Barrel of Paint". The term was also used during the World War II period in the United States. In 1940, Time quoted the U.S. Army on managing the military draft efficiently: "War is not going to wait while every slacker resorts to endless appeals."
The shift in the use of "slacker" from its draft-related meaning to a more general sense of the avoidance of work is unclear. In April 1948, The New Republic referred to "resentment against taxes levied to aid slackers". An article tracking the evolution of the meaning of the term "Slacker" in defamation lawsuits between World War I and 2010, entitled When Slacker Was a Dirty Word: Defamation and Draft Dodging During World War I, was written by Attorney David Kluft for the Trademark and Copyright Law Blog.
The term achieved renewed popularity following its use in the 1985 film Back to the Future in which James Tolkan's character Mr. Strickland chronically refers to Marty McFly, his father, Biff Tannen, and a group of teenage gangsters in Part II as "slackers"." It gained subsequent exposure from the 1989 Superchunk single "Slack Motherfucker", and the 1991 film Slacker.Slacker became widely used in the 1990s to refer to a subset of apathetic youth who were cynical and uninterested in political or social causes and as a stereotype for members of Generation X.