tunga (ON) noun

Literally 'tongue'. Men who did not speak Norse were exempted from fines to the bishop related to the eating of horse flesh (GuL ch. 20). It seems to have been required that oaths were to be taken in the Norse language (GuL ch. 24).

language ONorw GuL Krb
Expressions:

mista tungo (OSw)

lose the tongue OSw MESt Kb, Rb

Refs:

KLNM s.v. dansk tunge