What does "lighten" mean?

Lighten: To burst forth or dart, as lightning; to shine with, or like, lightning; to display a flash or flashes of lightning; to flash. This dreadful night, That thunders, lightens, opens graves, and roars As doth the lion. Shak.

Additional senses

  1. 2.To grow lighter; to become less dark or lowering; to brighten; to clear, as the sky.
  2. 3.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.] A key of fire ran all along the shore, And lightened all the river with a blaze. Dryden.
  3. 4.To illuminate with knowledge; to enlighten. [In this sense less common than enlighten.] Lighten my spirit with one clear heavenly ray. Sir J. Davies.
  4. 5.To emit or disclose in, or as in, lightning; to flash out, like lightning. His eye . . . lightens forth Controlling majesty. Shak.
  5. 6.To free from trouble and fill with joy. They looked unto him, were lightened. Ps. xxxiv.
  6. 7.1. 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.
  7. 8.To make less burdensome or afflictive; to alleviate; as, to lighten the cares of life or the burden of grief.
  8. 9.To cheer; to exhilarate. Lighens my humor with his merry jests. Shak.

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