a. The diffused light from the sky during the early evening or early morning when the sun is below the horizon and its light is refracted by the earth's atmosphere.
b. The time of the day when the sun is just below the horizon, especially the period between sunset and dark.
2. Dim or diffused illumination.
3. A period or condition of decline following growth, glory, or success: in the twilight of his life.
4. A state of ambiguity or obscurity.
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