The phrase "main bedroom" refers to the largest or most important bedroom in a house or apartment. It is usually where the owners or primary occupants sleep. Full definition
The air - conditioned main bedroom contains a double bed and an en suite. (travelground.com)
Lower level contains main bedroom with a queen size bed plus an ensuite with twin showers. (alluxia.com)
Modern 2 bedroom unit with restful colours, comfortable queen size bed in main bedroom, bunk beds in the 2nd bedroom and a fold up bed and cot available on request. (wikiaustralia.com)