What does "small hours" mean?

The very early morning, just after midnight, when most people are asleep.

What is a synonym for "small hours"?

Common synonyms include: alpenglow, aurora, belatedness, crepuscule, dawnlight, eleventh hour.

noun

noun ·Rare ·Advanced level

Noun

1
The very early morning, just after midnight, when most people are asleep. plural, plural-only
"Cologne Hauptbahnhof is reached in the small hours, and the traveller new to postwar Germany is spared the sight of the devastated city."
2
the hours just after midnight wordnet

"Cologne Hauptbahnhof is reached in the small hours, and the traveller new to postwar Germany is spared the sight of the devastated city."

From the small number used to identify such hours (e.g. 1 o'clock, 2 o'clock).