Do you know anyone lazy or slothful? Then you know a sluggard: an idle or sluggish person.
If you know that sluggish means slow-moving, then you have a clue to the meaning of sluggard. A sluggard is a lazy, sleepy, slow-moving person. A sluggard is likely to oversleep and even snooze through class or work. If you're alert and hard-working, no one will ever call you a sluggard or a slug. Being a sluggard is a great way to fail a class, lose a job, or just fall behind in general.