Dawn vs. Predawn

Dawnverb

(intransitive) To begin to brighten with daylight.

‘A new day dawns.’;

Predawnnoun

Period before the rising of the sun.

Dawnverb

(intransitive) To start to appear or be realized.

‘I don’t want to be there when the truth dawns on him.’;

Dawnverb

(intransitive) To begin to give promise; to begin to appear or to expand.

Dawnnoun

(uncountable) The morning twilight period immediately before sunrise.

Dawnnoun

(countable) The rising of the sun.

Dawnnoun

(uncountable) The time when the sun rises.

‘She rose before dawn to meet the train.’;

Dawnnoun

(uncountable) The beginning.

‘the dawn of civilization’;

Dawnverb

To begin to grow light in the morning; to grow light; to break, or begin to appear; as, the day dawns; the morning dawns.

‘In the end of the Sabbath, as it began to dawn toward the first day of the week, came Mary Magdalene . . . to see the sepulcher.’;

Dawnverb

To began to give promise; to begin to appear or to expand.

‘When life awakes, and dawns at every line.’; ‘Dawn on our darkness and lend us thine aid.’;

Dawnnoun

The break of day; the first appearance of light in the morning; show of approaching sunrise.

‘And oft at dawn, deep noon, or falling eve.’; ‘No sun, no moon, no morn, no noon,No dawn, no dusk, no proper time of day.’;

Dawnnoun

First opening or expansion; first appearance; beginning; rise.

‘These tender circumstances diffuse a dawn of serenity over the soul.’;

Dawnnoun

the first light of day;

‘we got up before dawn’; ‘they talked until morning’;

Dawnnoun

the earliest period;

‘the dawn of civilization’; ‘the morning of the world’;

Dawnnoun

an opening time period;

‘it was the dawn of the Roman Empire’;

Dawnverb

become clear or enter one's consciousness or emotions;

‘It dawned on him that she had betrayed him’; ‘she was penetrated with sorrow’;

Dawnverb

appear or develop;

‘The age of computers had dawned’;

Dawnverb

become light;

‘It started to dawn, and we had to get up’;

Dawn

Dawn is the time that marks the beginning of twilight before sunrise. It is recognized by the appearance of indirect sunlight being scattered in Earth's atmosphere, when the centre of the Sun's disc has reached 18° below the observer's horizon.