þynne
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.
þynne
. II. 2. AddÞá fatu þá þe hé geát ǽr swýðe lytelne dǽl þæs þynnestan wǽtan vasa in quibus tenuissimum liquorem infuderat. Gr. D. 59, 15.
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A Combined List of Abbreviations.

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A Combined List of Abbreviations.