aðtra
Aðtra is a term that appears in a small number of Icelandic-language texts and linguistic discussions. It is not a common modern word in Icelandic, and its precise meaning has not achieved wide consensus among scholars. In scholarly discussions, aðtra is typically treated as an archaic or marginal form rather than a standard lexical item.
Etymology and sense are uncertain. Some commentators suggest that the form may be related to verbs with
Attestations of aðtra are rare and largely confined to historical glossaries, marginal notes, or philological discussions
In broader reference, aðtra is sometimes cited in discussions of archaic verb formations or as an example