also: みずしも
noun
frozen dew; frosty dew
Refers to dew that has frozen, typically in late autumn. A seasonal word (kigo) for haiku.
晩秋の朝、草の上に水霜が降りていた。
On a late autumn morning, frozen dew lay on the grass.
noun
waters; amniotic fluid
Medical/obstetric term for amniotic fluid discharged shortly before birth. Often used in the phrase 水霜が破れる (the waters break).
See also: 羊水
出産間近に水霜が破れた。
Her waters broke shortly before delivery.
Compound of 水 (water) and 霜 (frost). The reading みずじも is a rendaku form of しも. The amniotic fluid sense is an extended metaphorical use, likely from the visual similarity of the clear fluid to frozen dew.