noun
bedroom; sleeping quarters
Often implies a married couple's bedroom; somewhat literary or old-fashioned. In modern casual speech, 寝室 (しんしつ) is more common.
夫婦は寝屋に戻った。
The couple returned to their bedroom.
古い日本家屋では、寝屋は奥まった場所にあった。
In old Japanese houses, the sleeping quarters were located in the back.
noun
inner room; back room
Refers to a room located deep inside a house, away from the entrance. This usage is rare and mostly found in descriptions of traditional architecture.
寝屋は家の一番奥にある部屋を指すこともある。
寝屋 can also refer to the innermost room of a house.
Compound of 寝 (ne, 'sleep') + 屋 (ya, 'room/house'). The kanji 閨 is a specific character for a bedroom, often a married couple's room, and is used as an alternative spelling.