first winter rain; first rain of the cold season
Archaic seasonal word (kigo) for the first rain that falls between late autumn and early winter, often associated with haiku and classical poetry.
The first winter rain — the sound of it falling into the old pond.
Compound of 初 (hatsu, 'first') and 時雨 (shigure, 'winter rain'). The exact historical derivation is uncertain, but the word is a traditional seasonal term.