An unglossed Quenya noun from notes Words, Phrases and Passages from the Lord of the Rings, apparently derived from primitive ✶rinse where the [[aq|[ns] became [ss]]] in Ancient Quenya (PE17/87). It was related to the final element of S. Imladris “Rivendell, (lit.) Deep Dale of the Cleft” and so perhaps means “✱cleft, ravine”.
Neo-Quenya: Given that its meaning is unknown, I’d avoid this word in Neo-Quenya, using other words like Q. (a)nacca or ᴹQ. yáwe instead.
rissë noun? The word is not clearly glossed but apparently means "cut" or "cleft" (ravine), the cognate of the final element of Imladris, Sindarin name of Rivendell. (PE17:87)