first ice of winter
Refers to the first thin ice that forms on ponds, puddles, or other surfaces at the beginning of winter. Often used in poetic or seasonal contexts.
今朝、池に初氷が張った。
This morning, the first ice of winter formed on the pond.
Compound of 初 (hatsu, 'first') and 氷 (kōri, 'ice'), with rendaku voicing of the second element.