From AMS Glossary
Same as rime, but especially applied to rime formation on aircraft.
Flight through an extremely supercooled cloud (-10°C or colder) is very conducive to rime icing. This type of ice weighs less than clear ice, but it may seriously distort airfoil shape and thereby diminish the lift. In aviation parlance, ice that has the ideal rime character may be called kernel ice, and that intermediate between rime and clear ice may be called milky ice.