noun, noun or participle which takes 'suru', intransitive verb
lying on one's side; lateral recumbent position
Formal or literary term for lying on one's side, often used in medical or descriptive contexts. Can be used as a noun or with する to mean 'to lie on one's side'.
患者は側臥の姿勢で休んでいる。
The patient is resting in a lateral recumbent position.
He was tired and lay down on his side on the floor.
noun, noun or participle which takes 'suru', intransitive verb
sleeping next to someone
Rare, formal/literary usage for sleeping beside another person. In modern Japanese, 添い寝 (そいね) is far more common for this meaning.
古典文学には、旅先で側臥する場面が描かれることがある。
In classical literature, there are sometimes scenes of sleeping next to someone while traveling.