Technically it’s morning. Not even an argument. My answer was purely based on the clock system. But I think the answer is actually a bit more complex depending on your location and time of year. After reading the definitions of Morning, Night, Day, Midnight, and AM/PM, my answer is that 12 AM can be Morning, Morning and Night, or Morning and Day. I do not believe 12 AM can solely be called Night based on the phrasing of your question. It seems like your uncle is conflating Afternoon (PM) and Night (period of time from sunset to sunrise). By definition 12 AM is the start of the morning hours or Ante Meridian. So by the clock system it’s Morning. The definition of Night is the period of time from sunset to sunrise. In many parts of the world during much of the year the sun has set when the clock strikes 12AM. Thus 12 AM is by definition both Night (no sunlight) and Morning (AM). There are parts of the world (think extreme North or extreme South) where the sun does not set for months. In these parts of the world, during these seasons of seemingly unending daylight, 12 AM is both Morning and Day. As Day is defined by the period of time from sunrise to sunset. If you really wanted to split hairs the final scenario that I can think of, is where 12 AM is simultaneously Midnight, Morning, and Night or Midnight, Morning, and Day. Depending on location, season, and the presence or absence of sunlight and the definition of midnight. Just don’t ask if 12 PM is considered Afternoon or Day. Answer from ScottyJobs on reddit.com