Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio.
the first few hours after midnight
Used by arrangement with John Wiley & Sons, Inc.
plural nounThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The early hours after midnight.
small hours - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Also, wee hours. The hours following midnight, as in I stayed up working through the small hours, or The parents didn't come home until the wee hours. The adjectives small and wee both refer to the low numbers of those hours (one o'clock, two o'clock, etc.). [c. 1830]