frost 英語で:

1. the cold weather conditions which allow a thin layer of powdery ice to form

英語 "という言葉frost"（the cold weather conditions which allow a thin layer of powdery ice to form）集合で発生します。

Angielski vocab 3 rozdzial

2. small white ice crystals formed on the ground when the temperature falls below freezing

英語 "という言葉frost"（small white ice crystals formed on the ground when the temperature falls below freezing）集合で発生します。

Activate B2! p18,20