The “Great Hall of Feasts” in Minas Tirith (LotR/975), a combination of mereth “feast” and rond “vaulted chamber” (SA/mereth).
Conceptual Development: This name was already N. Merethrond “Great Hall of Feasts” in Lord of the Rings drafts from the 1940s (SD/67).
[HKF] mereth (“feast”) + rond (“dome-roofed hall”) Nd doesn’t become nn>n at the end of fully accented monosyllables, such as thond.