lightning: [14] Etymologically, lightning is simply something that illuminates, or ‘lightens’, the sky. The word is a contraction of an earlier lightening, a derivative of lighten ‘make light’. The Old English word for ‘lightning’ was lēget, which is related to light. In Middle English it became leit, and later leiting, but in the 14th century lightning took over as the main form. => light
