A person who avoids work or responsibility and doesn't put in proper effort, especially when they could do better.
From the verb 'slack,' which comes from Old English 'slæc' meaning loose or careless, plus -er to make it a noun describing the type of person.
The term exploded in popularity in the 1990s with the 'Generation X' label, but people have been lazy since humans invented work—language just catches up with cultural moments.
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