Þrekvirki

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

þrekvirki

n. deed of derring-do (þetta er hit mesta ~).

Possible runic inscription in Younger Futhark:ᚦᚱᛁᚴᚢᛁᚱᚴᛁ

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