- þrettándi
- ord. numb. the thirteenth.* * *the thirteenth, passim.2. the thirteenth and last day of Yule, or the 6th day of Jan., is in Icel. called ‘Þrettándi,’ in Engl. Twelfth Night; see Icel. Almanack.
An Icelandic-English dictionary. Richard Cleasby and Gudbrand Vigfusson. 1874.