fíf-teóþa
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.
fíf-teóþa
AddSe fífteóða quintus decimus, Ælfc. G. Z. 283, 3. Under þám fífteóðan (-teogeþan, -tigeþan, -tegþan, -téþan, v. ll. ) geáre, Bd. 4, 17; Sch. 430, 22. Gér ðe fíftegða (ðió fífteiðe, L.) anno quinto decimo, Lk. R. 3, 1. Ðió fífteiðo, Lk. p. 4, 6. On þone fíftegðan dæg, Shrn. 104, 12.
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A Combined List of Abbreviations.