Definition: [verb] (especially of a liquid) flow over the brim of a receptacle.
Example: chemicals overflowed from a storage tank
Definition: [noun] the flowing over of a liquid.
Example: there was some overflow after heavy rainfall
Definition: [noun] (in a bath or sink) an outlet for excess water.
Definition: [noun] the generation of a number or other data item which is too large for the assigned location or memory space.