People who avoid work, responsibilities, or effort; lazy people or those who don't take things seriously.
From 'slack' (loose, not tight) combined with '-er' (one who does something). The meaning shifted from literally loose things to metaphorically loose attitudes about work.
The term 'slacker' became a major cultural identity in the 1990s—MTV's 'Beavis and Butt-Head' and movies like 'Slacker' turned it into a whole generational attitude about rejecting corporate work culture. Gen X basically owned this label before millennials made 'lazy' ironic.
Complete word intelligence in one call. Free tier — 50 lookups/day.