unc
This might be just a supplemental entry adding to an entry in the Main Volume.
Related §§ in Wright's OE Grammar:
In the OE text, the length is:indicated by acute accentsindicated by macronsnot indicated.
unc
Add: — Férdon mín fæder and módor út, and genámon unc and férdon tó sǽ, and út reówan. Þá wé úp cómon, þá næs úre módor mid ús, nát ic for hwí þá genam úre fæder unc, and bær ús wépende forð on his weg, Hml. S. 30.
This is a supplementary entry with editorial changes to an entry in the main volume of the dictionary. Look under the 'Possibly connected entries' below, or for the same headword in the list to the left.

A Combined List of Abbreviations.

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A Combined List of Abbreviations.