at the crack of dawn

US /æt ðə kræk əv dɔn/
UK /æt ðə kræk əv dɔn/
"at the crack of dawn" picture
1.

very early in the morning, at the first sign of light

:
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We had to leave at the crack of dawn to catch our flight.
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The farmers start their work at the crack of dawn.
:
dawndawn oncrackcrackedcrack oncrack down oncrack up