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
If you say that something will happen in the morning, you mean that it will happen during the morning of the following day. I'll fly it to London in the morning
If you say that something happens morning, noon and night, you mean that it happens all the time. You get fit by playing the game, day in, day out, morning, noon and night. used to greet someone in the morning
The morning is the part of each day between the time that people usually wake up and 12 o'clock noon or lunchtime. During the morning your guide will take you around the city On Sunday morning Bill was woken by the telephone He read about it in his morning paper
The first or early part of the day, variously understood as the earliest hours of light, the time near sunrise; the time from midnight to noon, from rising to noon, etc