This ancient Scandinavian rune means “intermittent.”
@dpnash @Quinnypig Apparently, there is no proof yet found that Denmark’s King Harald Gormsson was ever called Blåtand during his lifetime, as he died in 985 AD and the first BT mentions in writing dates back to 1140 AD, in the Roskilde Chronicle (https://en.wikipedia.org/wiki/Chronicon_Roskildense).
Source: article written by Dick Harrison (professor in history) at Lund University. I found the article in one of the big-name newspapers in Sweden, SvD (Svenska Dagbladet): https://www.svd.se/a/QVmKP/kommer-smeknamnet-av-kassa-tander