v. i. [ imp. & p. p. Lightened p. pr. & vb. n. Lightening. ] [ OE. lightenen. See Light to kindle, illuminate. ] 1. To burst forth or dart, as lightning; to shine with, or like, lightning; to display a flash or flashes of lightning; to flash. [ 1913 Webster ]

This dreadful night,
That thunders, lightens, opens graves, and roars
As doth the lion. Shak. [ 1913 Webster ]

2. To grow lighter; to become less dark or lowering; to brighten; to clear, as the sky. [ 1913 Webster ]

v. t. [ See Light to illuminate. ] 1. To make light or clear; to light; to illuminate; as, to lighten an apartment with lamps or gas; to lighten the streets. [ In this sense less common than light. ] [ 1913 Webster ]

A key of fire ran all along the shore,
And lightened all the river with a blaze. Dryden. [ 1913 Webster ]

2. To illuminate with knowledge; to enlighten. [ In this sense less common than enlighten. ] [ 1913 Webster ]

Lighten my spirit with one clear heavenly ray. Sir J. Davies. [ 1913 Webster ]

3. To emit or disclose in, or as in, lightning; to flash out, like lightning. [ 1913 Webster ]

His eye . . . lightens forth
Controlling majesty. Shak. [ 1913 Webster ]

4. To free from trouble and fill with joy. [ 1913 Webster ]

They looked unto him, and were lightened. Ps. xxxiv. 5. [ 1913 Webster ]

v. t. [ See Light not heavy. ] 1. To make lighter, or less heavy; to reduce in weight; to relieve of part of a load or burden; as, to lighten a ship by unloading; to lighten a load or burden. [ 1913 Webster ]

2. To make less burdensome or afflictive; to alleviate; as, to lighten the cares of life or the burden of grief. [ 1913 Webster ]

3. To cheer; to exhilarate. [ 1913 Webster ]

Lightens my humor with his merry jests. Shak. [ 1913 Webster ]

v. i. [ See Light to alight. ] To descend; to light. [ 1913 Webster ]

O Lord, let thy mercy lighten upon us. Book of Common Prayer [ Eng. Ed. ]. [ 1913 Webster ]

n. The process of changing to a lighter color.
Syn. -- whitening. [ WordNet 1.5 ]