DCHP-2

ensuite en suite < French en suite 'in sequence' DCHP-2 (October 2016)

• 1 adv. — Housing

  creating a single unit among neighbouring rooms; a room that can be entered through another room.

  Type: 5. Frequency — While ensuite is used widely, it occurs three times more frequently in Canada than in the US (see Chart 1). The adverbial meaning is the oldest one: adjacent rooms could be used or were placed "ensuite". This meaning gave rise first to the adjectival use (meaning 2) and later to the use as a noun (meaning 3), with the present meaning receding in importance.
  See also COD-2, which labels the adverbial function as "Cdn & Brit.".

• 2 adj. — Housing

  referring to a bathroom attached to a bedroom; in older examples, to two attached rooms, room & laundry room or the like.

  Type: 5. Frequency — Referring to meaning 1, adjectival meanings were the first extension, which is one of today's most widely used meanings.

• 3 n. — Housing

  a bathroom that is entered through a bedroom, usually the master bedroom.

  Type: 5. Frequency — The conversion into a noun is the most recent development. As can be seen in the 1968 quotation, it has been in use for quite a while and is today perhaps the most common use of the term.