noun

the first appearance of light in the sky before sunrise.

he set off at dawn

daybreak,break of day,crack of dawn,sunrise,first light,daylight,first thing in the morning,early morning,cockcrow,sunup,dawning,peep of day,aurora,dayspring

verb

(of a day) begin.

Thursday dawned bright and sunny

begin,open,break,arrive,emerge,grow light,lighten,brighten