Oh dark thirty noun phrase
The word "oh" is a way of expressing the number zero.
Used to indicate a period of time in the early morning after midnight but before sunrise
It’s a nuisance having to get up at oh dark thirty.
If you want to reach the destination on time, you will have to depart at oh-dark-thirty.
Soldiers will march at oh dark thirty.
Very early or very late.
Suggest someone or oneself for consideration in a selection, such as a competition, application pool, election, etc.
Kamala Harris is expected to put her name on the hat for the US president.