certh (“sickle”) + in (gen. pl. article) + Belain (pl. of Balan Power) The lenition of Balain to Mbelain reflects Tolkien's earlier view of nasal mutation, where b, d, g > mb, nd, ng [HKF]; or it could possibly be an archaic form.
Quenya
valacirca
proper name. Sickle of the Valar
A constellation of seven stars (S/48), the Elvish version of the constellation of the Great Bear (SI/Valacirca), known as the Big Dipper by Americans or the Plough in Britain. It is a compound of Vala and the noun circa “sickle”.
Conceptual Development: A constellation of Seven Stars is mentioned in the earliest Lost Tales (LT1/114). In the Qenya Lexicon, the name ᴱQ. Telpea Kalka “✱Silvern Sickle” is given to the Great Bear (QL/47). The name “Sickle of the Gods" for this constellation emerged in Silmarillion drafts from the 1930s (LR/212), and its Quenya name ᴹQ. Valakirka appears in The Etymologies from the same period (Ety/KIRIK). The Quenya name Valacirca did not appear in the tales themselves until Silmarillion revisions from the 1950s-60s (MR/71).