√YU root. “both”
This Elvish root was connected to the sense “two” or “both” throughout Tolkien’s life. The first clear manifestation of this root was ᴱQ. yú “twice” and ᴱQ. yúyo “two” from the Early Qenya Grammar of the 1920s (PE14/49-51, 82-84). The root ᴹ√YŪ “two, both” appeared in The Etymologies of the 1930s with derivatives like ᴹQ. yúyo “both” and ᴹQ. yúkale/N. uial “twilight” (Ety/KAL, YŪ). The root √YU appeared several times in Tolkien’s later writings, generally with the sense “both” (PE17/70; PE21/74; VT48/8, 10). It was likely related to the ancient dual suffix ✶-ū.
References ✧ PE17/70; PE21/74; VT48/8, 10
ᴹ√YŪ root. “two, both”
References ✧ Ety/AY, KAL, YŪ