undern
This might be just a supplemental entry adding to an entry in the Main Volume.
In the OE text, the length is:indicated by acute accentsindicated by macronsnot indicated.
undern
Add:I. the third hour of the day Hé hét þæt hí áne tíd ofer undern (cf. æt þǽre þriddan tíde on morgenne, Bl. H. 201, 35) hí getrymedon ongeán heora fýnd, Hml. Th. i. 504; 24. II. the service of the church at the third hour Þysum gesungenum cweðan gebed drihtenlice. Þáræfter fylige undern (tertia ). Þám geendedum . . . , Angl. xiii. 404, 554. Underne gedónum tertia peracla, 388, 330.
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A Combined List of Abbreviations.