western side house (in traditional palatial-style architecture)
Refers to the western auxiliary building in a shinden-zukuri (寝殿造) complex, typically connected by corridors to the main hall.
See also: 寝殿造り
In shinden-zukuri, the western side house was mainly used as living quarters for the family.
Compound of 西 (nishi, 'west') + の (no, possessive particle) + 対 (tai, 'opposite' or 'paired building'). The term is specific to Heian-period aristocratic residential architecture.