A hypothetical (Sindarin-only?) root serving as the basis for Sindarin words like dîn “silence” and dínen “silent” (PE17/95, 98). Tolkien’s use of these words in The Lord of the Rings is rather inconsistent, reflecting shifting rules on the circumstances in which words mutated in Sindarin. In his Unfinished Index of The Lord of the Rings, he said these words were tîn and tínen (RC/551). Given the conflict this would have with the root √TIN “spark”, for purposes of Neo-Eldarin I think it is best to assume this root is √DIN.