Middle Primitive Elvish
(n)dew
root. follow, come behind
khil
root. follow
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
A root in The Etymologies of the 1930s glossed “follow, come behind”, apparently a strengthened form of ᴹ√DEW (Ety/NDEW; EtyAC/DEW). Its most notable derivative is Doriathrin name Dior “successor”, name of Thingol’s grandson and heir after the departure of his parents Beren and Lúthien. This name dates back to the earliest versions of the legendarium, and Tolkien continued to use it in later versions of the Silmarillion, but this is the only place he gave it a derivation. However, Dior cannot be a derivative of √NDEW in Sindarin, since [[os|[eu] became [iu]]] and then became [ȳ] (VT47/7), so that the result would be ✱dŷr in Sindarin. Most likely Dior was one of those names Tolkien retained from the earliest iteration of the legendarium despite it no longer having any clear etymological foundation in later versions of the Elvish languages.