In the north, it is called Breakfast, Lunch, and Dinner.
In the south, it is called Breakfast, Dinner, and Supper.
Somewhere along the way, someone invented 'Brunch' as an in-between for 'Breakfast' and 'Lunch'.
At times, 'Dinner' does get confusing!
How about this:
Breakfast: from 6 AM to 9 AM
Brunch: from 9 AM to 12 PM
Lunch: from 12 PM to 3 PM
Dinner: from 3 PM to 6 PM
Supper: from 6 PM to 9 PM
Between 3 AM and 6 AM is early breakfast.
Between 9 PM and 12 AM is late supper.
Between 12 AM and 3 AM --- call it whatever you like...