The day after the present day.
"I have to leave for work tomorrow since my shift starts at eight in the morning."
In plain English: Tomorrow is the day that comes after today.
"The weather forecast for tomorrow looks promising."
Usage: Use tomorrow as a noun to refer specifically to the next 24-hour period, often with an article like the or in phrases such as this time tomorrow. It is interchangeable with "tomorrow morning" when specifying that part of the future day but implies only the immediate following calendar date.
the next day, the day after, following the present day
"I'll start my new job tomorrow since I finish my current contract today."
On the day after the present day.
"I will meet you tomorrow at noon for our lunch date."
In plain English: Tomorrow is used to talk about something that will happen after today.
"I will meet you here tomorrow."
The word tomorrow comes from Old English, originally combining "at" with the dative form of morning to mean "at morning." It traveled into modern English as a straightforward adverb indicating the day after today.