A word in a list of “large & small” roots from the late 1960s glossed “mighty, masterful” along with an equivalent word túrëa, both derived from √TUR “strong, mighty, in power” (PE17/115). In notes associated with the Quendi and Eldar essay of 1959-60, Tolkien glossed it as “very mighty, vast, of unmeasured might or size” as an example of ancient a-fortification of the root √TUR (VT39/10). ᴹQ. taura “mighty” appeared in The Etymologies of the 1930s derived from primitive ᴹ✶taurā under the root ᴹ√TUR “power, control, mastery, victory” (Ety/TUR).
Neo-Quenya: For purposes of Neo-Quenya, I would assume this word applies to general might and majesty, applicable to people but also to inanimate things, as in i taura ëaron “the mighty ocean = the vast and powerful ocean”. I would use túrëa more specifically for someone who is politically powerful, having mastery or influence over others.
taura adj. "mighty, masterful" (TUR, PE17:115), "very mighty, vast, of unmeasured might or size" (VT39:10). Cf. túrëa.