The definition of a slacker is an unmotivated person who doesn't work very hard or who doesn't have a lot of ambition.
A guy who sits around on the couch all day and does nothing productive is an example of a slacker.
- a person who shirks work or duty
- a person who evades military service in wartime
- Informal a young person, typically in his or her twenties, variously regarded as idle, lazy, unambitious, etc.
- One who shirks work or responsibility.
- One who tries to evade military service in wartime; a draft dodger.
From slack +"Ž -er; compare especially slack off.