Kafsyndr

As defined by A Concise Dictionary of Old Icelandic (Geir Zoëga):

kafsyndr

a. good at swimming under water.

Possible runic inscription in Younger Futhark:ᚴᛅᚠᛋᚢᚾᛏᚱ

Also available in related dictionaries:

This headword also appears in dictionaries of other languages closely related to Old Icelandic.

• Old Norse - Cleasby & Vigfusson Dictionary
• Old Norwegian - Johan Fritzner's Dictionary