Many people greet someone with the shortened "morning" rather than "good morning". It is used as a greeting, never a farewell, unlike good night which is used as the latter.
Pertaining to the first part or early part of the day; being in the early part of the day; as, morning dew; morning light; morning service. [ 1913 Webster ] She looks as clear
MORNING meaning: 1. the part of the day from the time when the sun rises or you wake up until the middle of the day…. Learn more.
I'm a morning person. [= a person who likes or has more energy in the early part of the day] c : the time from midnight to noon
If you refer to a particular time in the morning, you mean a time between 12 o'clock midnight and 12 o'clock noon. I often stayed up until two or three in the morning. 3.
the first period of the day, usually from dawn, but sometimes considered from midnight, up to noon: [uncountable] On Monday morning we arrived at work. [countable] On Monday mornings she usually comes to work late.
One morning I had been driven to the precarious refuge afforded by the steps of the inn, after rejecting offers from the Celebrity to join him in a variety of amusements.
Morning definition: The first or early part of the day, lasting from midnight to noon or from sunrise to noon.
There are ten meanings listed in OED's entry for the word morning, one of which is labelled obsolete. See ‘Meaning & use’ for definitions, usage, and quotation evidence.