Þrinna

According to the Old English Dictionary:

. This seems a Scandinavian form [cf.

þrinna

Icel. þrennar tylftir three twelves; e.g. þrennar tylftir eigu at dæma málit, Njála c. 144] :-- Ládige hé hine mid þrinna .xii., L. Eth. iii. 13; Th. i. 296, 29. þrinna