A sickness bag (also known as a sick sack, airsick bag, airsickness bag, emesis bag, sick bag, barf bag, vomit bag or motion sickness bag) is a small bag commonly provided to passengers on board airplanes and boats to collect and contain vomit in the event of motion sickness.  Hovercraft-ferry operators and even train companies have also been known to supply bags. Pregnant women with morning sickness and travelers who know they are prone to motion sickness will sometimes bring their own bags.