As defined by the Cleasby & Vigfusson Old Norse to English dictionary:
- adj. blue-cold, of purling water or iron, cp. the phrase, berja fram blákalt, hammering the iron cold, of obstinate, dogged reasoning.
Possible runic inscription in Younger Futhark:ᛒᛚᛅ-ᚴᛅᛚᛏᚱ
Younger Futhark runes were used from 8th to 12th centuries in Scandinavia and their overseas settlements