Trosna

As defined by the Cleasby & Vigfusson Old Norse to English dictionary:

trosna

að, to ‘fall into tros,’ split up, of a seam or the like.

Possible runic inscription in Younger Futhark:ᛏᚱᚢᛋᚾᛅ
Younger Futhark runes were used from 8th to 12th centuries in Scandinavia and their overseas settlements