The least valuable or most undesirable part of something; sediment or grounds that settle at the bottom of a liquid.
From Middle English 'dreg', possibly from Old Norse 'dregg' or related Scandinavian words. Often used in plural 'dregs', referring to the bottom sediment of wine or the worst parts of society.
The phrase 'the dregs of society' is old—it metaphorically treated human cast-offs like they were sediment settling to the bottom, a surprisingly visual way to express social hierarchy.
Complete word intelligence in one call. Free tier — 50 lookups/day.