The noun ᴱQ. sutl “sticky matter, slime, gum” appeared in the Qenya Lexicon of the 1910s as a derivative of the root ᴱ√SUKU¹ (QL/86-87). Its Gnomish equivalents like G. thuith and G. thugli indicate the actual root form was *ᴱ√ÞUKU, so probably ᴱQ. sutl < *þukl with -kl > -tl as often happened in Early Qenya words.

Neo-Quenya: I think this word might be salvagable for purposes of Neo-Quenya as ᴺQ. sucul [þ] “sticky matter, slime”, a less viscous variant of ᴺQ. suhtë “resin, gum”. Another later word of similar meaning ᴹQ. makso “sticky substance, mire”.