A smaller bar than that which you get in your high-priced room at the better hotels. Also called a minibar.
(Better answers are given elsewhere on the thread)
A millibar has real teeny bottles.
A millibar is one thousandth of the standard barometric pressure. A bar is one atmosphere of pressure. At sea level one bar is said to be 1013 millibars, so there are really more than a thousand millibars in a bar. There must be a reason for it such as determining the average pressure from some geographical point on earth, maybe London, that is not quite at sea level where the pressure would be one bar equals 1000 millibars.