Meaning

• To make brighter or clearer; to illuminate.

  "to lighten an apartment with lamps or gas; to lighten the streets"

• To become brighter or clearer; to brighten.

• To burst forth or dart, as lightning; to shine with, or like, lightning; to flash.

• To emit or disclose in, or as if in, lightning; to flash out, like lightning.

• To illuminate with knowledge; to enlighten.