A: In its simplest explanation, negligence is carelessness. Contributory means that you have participated in the carelessness.
When an injured victim brings a lawsuit, the defense will typically claim that the person who brought the lawsuit is either partially at fault or fully at fault for causing their own injury.
They will often claim that the plaintiff, the person who is bringing the lawsuit is contributorily negligent. They will typically deny that they had anything to do with causing the victim's injuries and instead place the blame on the injured victim saying that they caused or contributed as a result of their own carelessness.