Early Primitive Elvish
luhu
root. *time
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
lu
root. *time
This root and ones like it were the basis for time words throughout Tolkien’s life. The earliest appearance of this root was as ᴱ√LUHU or ᴱ√LU’U (the latter marked by Tolkien with a “?”) in the Qenya Lexicon of the 1910s, unglossed but with derivatives like ᴱQ. lú “24 hours, day” and ᴱQ. lúme “time” (QL/56). It also had derivatives in the contemporaneous Gnomish Lexicon like G. lu “occasion, time” and G. lust “time; tide; weather” (GL/55). It appeared as unglossed ᴹ√LU in The Etymologies of the 1930s with derivatives like ᴹQ. lú “a time, occasion”, ᴹQ. lúme “time”, and their Noldorin cognate N. lhû (Ety/LU).
The Etymologies had a distinct root ᴹ√ULU “pour, flow” (Ety/ULU). It was not explicity connected to ᴹ√LU in this 1930s document, but in notes from around 1959 Tolkien said lūmē “time” was derived from √ULU “flow” (PE17/168), so it is likely that √LU is an inversion of this more basic root.