To flow or run over the edge or brim of a container or area. The water began to overspill from the bathtub when the tap was left running.
To spread beyond the limits or boundaries of a particular area. The festival's popularity caused the crowd to overspill into the neighboring streets.
To cause (a liquid or other substance) to overflow its container; to spill over. She accidentally overspilled the milk while pouring it into the glass.