Definitions:

1. A personification of frost, ice, snow, sleet, winter, and freezing cold; he's a variant of Old Man Winter, who is responsible for frosty weather. NOUN
   • If everything has frozen in winter, the Jack Frost has visited.
2. According to English folklore, Jack Frost is an elf-like creature that leaves frost on windows during cold nights. NOUN
   • Look what pretty patterns Jack Frost has painted on the windows.

Synonyms:

• cold weather
• frost
• frostwork
• touch of frost