frost

Concise Oxford English Dictionary © 2008 Oxford University Press:
frost/frɒst/

▶noun

• 1 a deposit of small white ice crystals formed on the ground or other surfaces when the temperature falls below freezing.

• 2 a period of cold weather when frost forms.

▶verb

• 1 cover or be covered with or as if with frost; freeze.

• 2 N. Amer. decorate with icing.

– phrases
degrees of frost Brit. degrees below freezing point.

– derivatives
frostless adjective.

– origin OE frost, forst, of Gmc origin; rel. to freeze.