Speaking as a violinist of sorts...
Yeah... they're called stops. Double stops are rather easy and they aren't too uncommon. Harder music has triple stops occasionally. Some really old and not often played music calls for quadruple stops. To play a quadruple stop, you have to use an old style bow. The bow has to curve outward, unlike modern bows that curve inward. Most people just play it as an arpeggio, however.
Any other questions?