Primitive elvish
sub
root. sink (esp. in water)
Derivatives
Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
Middle Primitive Elvish
sub
root. sink (esp. in water)
Derivatives
The root ᴹ√SUB “sink, esp. in water” appeared in a rejected page of verbal roots from the Quenya Verbal System of the 1940s where it had a derived past tense form ᴹQ. sumbe “✱sank” as well as a distinct verb form ᴹQ. sumba- “to submerge” (PE22/127). It might be a later iteration of the unglossed root ᴱ√SUQU in the Qenya Lexicon of the 1910s, with derivatives like ᴱQ. sunqa “going down, descending; abysmal, deep, profound” and ᴱQ. suq- “fall, fail, go down, die down” (QL/87).
Neo-Eldarin: I think it is worth retaining ᴺ√SUB “sink” as a Neo-Root.