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).
Definition of rime frost in US English:
rime frost
nounˈrʌɪm frɒst
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).