kná

From Proto-Germanic *knēaną, whence also English know. Ultimately from Proto-Indo-European *ǵneh₃- (“to know”).

kná

1. (defective) can, could
   • c. 9th century, inscription on the Rök runestone

     sakum| |mukmini uaim si burin| |niþʀ troki uilin is þat knuo knati| |iatun

     Sǫgum múgminni/ungmenni, hveim sé borinn niðr drengi. Vilinn er þat. Knúa/knýja knátti jǫtun.

     I say the folktale/to the young men, to whom is born a relative, to a valiant man. It is Vélinn. He could crush a giant.

This verb is defective. Notably, the expected infinitive *knega is unattested.

• Icelandic: knega

• Zoëga, Geir T. (1910) “kná”, in A Concise Dictionary of Old Icelandic, Oxford: Clarendon Press, page 244; also available at the Internet Archive