A Sindarin word for “sixth” appearing in notes on numbers associated with The Rivers and Beacon-hills of Gondor from the late 1960s, an adjective form of eneg “six” using the suffix -ui, with a longer variant enecthui (VT42/25). In author’s note 5 of that document, Tolkien said that enchui was from the Southern dialect of Sindarin, saying that medial nasal-stop combinations like nc survived North Sindarin and implying the word was encui in that dialect (VT42/27). See the entry on canthui “fourth” for a discussion of the phonetic developments.

Earlier drafts of The Rivers and Beacon-hills of Gondor had encui and {enegui >>} enchui “fourth” (VT42/10; VT42/28 note #20), perhaps representing the North/South Sindarin pronunciations (or archaic vs. modern).

Neo-Sindarin: For purposes of Neo-Sindarin, I use the form enchui “fourth” to represent this word as it is spelled. In terms of pronunciation, any of enchui, enghui, or engui are possible, but I favor the pronunciation enchui for simplicity.