þri-milce, m.n: the old name for the month of May, “three-milkings”. (“three-mill-cheh”)

Detail of a miniature of woman milking a cow, who is licking its calf. England, S. (Salisbury?), 2nd quarter of the 13th century. British Library, MS Harley 4751, fol. 23. From The British Library.
Swylce in burh raϸe
[embe syx niht ϸæs], smicere on gearwum,
wudum and wyrtum cymeð wlitig scriðan
Þrymilce on tun; ϸearfe bringeð
Maius micle geond menigeo gehwær.
—The Old English Metrical Calendar (Menologium), lines 75b-79
Likewise, after six nights, beautiful Þrymylce comes gliding quickly into the citadel, into town, elegantly clad in adornments, woods and plants; May brings much of what is needed among a multitude of people everywhere. (trans. by K. Karasawa)
According to Bede’s De temporum ratione, May “used to be called Thrimilchi because in that month cows were milked three times a day, such was the fertility of Britain or Germania, from which the nation of the Angles migrated to Britain” (Karasawa, p. 101).
See Kazutomo Karasawa’s The Old English Metrical Calendar (Menologium) (Cambridge, 2015).