oh dark hundred

• 0-dark-hundred

From military time, in which hours before 10:00 am are prefixed with a zero, read as "oh", and 00 minutes is read as "hundred", as in oh five-hundred for 5:00 am.

oh dark hundred

1. (idiomatic) Some unspecified hour in the early morning (implies an unpleasant time to be awake)

   I had to get up at oh dark hundred to catch a plane.

• crack of dawn, stupid o'clock, wee small hours; see also Thesaurus:early morning

• 0-dark-thirty
• dark thirty
• oh dark thirty
• zero dark thirty