Noun (slang)

  • AKA Oh Dark Thirty. Very late at night or very early in the morning (usually before dawn).


Unknown. Modern times.


No, I’m not referring to the film about the tracking down of Osama Bin Laden.

This is a common military expression usually referring to a non-specific time either very late at night or very early in the morning. It references the use of military time (24-hour clock), where times before 10 AM are written starting with a zero. For example, 5:30 AM would be written as 0530 and pronounced, “zero five thirty,” or “oh five thirty.”

Tired sailors shuffling around in the dark:

“What time is it, bro?”

“I dunno. Zero dark thirty.”


Crowell, J. (2003, October 31). Naval Terminology, Jargon and Slang FAQ Part 2 – N through Z. Retrieved from