From Longman Dictionary of Contemporary Englishslackerslack‧er /ˈslækə $ -ər/ noun [countable] informal LAZYsomeone who is lazy and does not do all the work they should – used to show disapproval
Examples from the Corpus
slacker• Left to my own devices, this device has grown to be a slacker.• And Evans is hardly a slacker in the invertebrate department himself.• And therefore no slackers allowed! no deadwood! no lightweights! no loafers!• Those moments are nearly profound, and elevate the film above the slacker cliches in which it wallows. 