noun
sleeping in a ship
Literally sleeping aboard a vessel, often with a sense of floating on the water.
船旅では、波の揺れを感じながらの浮き寝も悪くない。
On a ship journey, sleeping while feeling the rocking of the waves isn't so bad.
noun
sleeping on the water's surface (of a bird)
Describes waterfowl resting while floating.
鴨が池の上で浮き寝をしている。
Ducks are sleeping on the surface of the pond.
noun
restless sleep
Sleep that is light and easily disturbed, as if floating.
心配事があって、昨夜は浮き寝だった。
With worries on my mind, I had a restless sleep last night.
noun
casually sleeping together (e.g. unmarried couple)
Implies an informal, possibly transient co-sleeping arrangement, often with romantic or sexual connotations.
昔の物語には、未婚の男女の浮き寝が描かれることがある。
In old tales, unmarried men and women casually sleeping together is sometimes depicted.
Compound of 浮き (uki, 'floating') + 寝 (ne, 'sleep'). The exact historical derivation is uncertain, but the word literally means 'floating sleep'.