sēlost, superl.adj: best. (“seh-lohst”)
8 September is the Nativity of Mary, cwena selost, the best of women.
…and þy seofoþan dæg / þæt acenned wearð cwena selost, / drihtnes modor.
– Old English Metrical Calendar (Menologium), lines 167b-169a
…and it is on the seventh day that the best of women, the Lord’s mother, was born.
– translation by Kazutomo Karasawa
Karasawa explains that the poet means the seventh day counting from 1 September, i.e. the 8 of September. The Nativity of St Mary the Virgin is “the last of the four Marian feasts venerated in the Roman church”. Karasawa says, “Mary’s birth is not recorded in the Bible but is traditionally celebrated on 8 September, nine months after her Immaculate Conception on 8 December.” The phrase cwena selost, “the best of women”, is a phrase for the Virgin Mary that is attested nowhere else, although she has also been called seo clæneste cwen (“the purest woman”), seo halige cwen (“the holy woman”), and ða ealra femna cwen (“the queen of all women”).*
*Kazutomo Karasawa, The Old English Metrical Calendar (Menologium) (Cambridge: D. S. Brewer, 2015), p. 117