Definition from Wiktionary, the free dictionary
Cognate with Old Norse misseri (“a season (of six months)”). Possibly related to mæl from Proto-Germanic *mēlą (“measure, time, occassion”), ultimately from Proto-Indo-European root *meh₁- (“to measure”).
missēre n (nominative plural missēru)
- Sona þæt onfunde, se ðe floda begong heorogifre beheold hund missera. At once he found her, who had guarded the water's realm ravenously for a hundred half-years. (Beowulf, ll. 1498-9)