master bedroom

From master (“head of household”) +‎ bedroom.

master bedroom (plural master bedrooms)

1. A room in a house, in which the head of the household sleeps, typically larger and better furnished than other bedrooms.
   • 2020 September 1, Tom Lamont, “The butcher's shop that lasted 300 years (give or take)”, in The Guardian‎:

     His entire adult life he had lived in the two-bed flat above the shop, sharing the space with his parents. Frank was in the spare room at the back. His parents had the master bedroom, with a big sash window that overlooked the high street.

• Regarding the use of master: the term was first used circa 1910, long after the abolition of slavery in the US, and there is no evidence that this term has any relation to or allusion to the practice of slavery.

• primary bedroom