Merriam-Webster's Collegiate® Dictionary, 11th Edition
DAWN
I. intransitive verb
Etymology: Middle English, probably back-formation from dawning daybreak, alteration of dawing, from Old English dagung, from dagian
Date: 15th century
to begin to grow light as the sun rises, to begin to appear or develop, to begin to be perceived or understood ,
II. noun
Date: 15th century
the first appearance of light in the morning followed by sunrise, beginning