Definition of rime frost in US English:

rime frost

noun

  • Hoar frost, rime.

Origin

Old English; earliest use found in The Lambeth Psalter. From rime + frost. Compare Icelandic hrímfrost, Old Swedish rimfrost (Swedish rimfrost), Old Danish rimfrost (Danish rimfrost).

Pronunciation

rime frost

/ˈrʌɪm frɒst/