LIGHTNING, n. li'tening. [that is, lightening, the participle present of lighten.]

1. A sudden discharge of electricity from a cloud to the earth, or from the earth to a cloud, or from one cloud to another, that is, from a body positively charged to one negatively charged, producing a vivid flash of light, and usually a loud report, called thunder. Sometimes lightning is a mere instantaneous flash of light without thunder, as heat-lightning, lightning seen by reflection, the flash being beyond the limits of our horizon.

2. [from lighten, to diminish weight.] Abatement; alleviation; mitigation.