A wandering troop or gang; especially, a clan or tribe of a nomadic people (originally Tatars) migrating from place to place for the sake of pasturage, plunder, etc.; a predatory multitude
If you describe a crowd of people as a horde, you mean that the crowd is very large and excited and, often, rather frightening or unpleasant. This attracts hordes of tourists to Las Vegas. a large crowd moving in a noisy uncontrolled way horde of (and , from horda)