An adjective in The Etymologies of the 1930s glossed “mighty, vast, overwhelming, huge, awful” derived from primitive ᴹ✶taurā “masterful, mighty” based on the root ᴹ√TUR “power, control, mastery, victory” (Ety/TÁWAR, TUR). It was also influenced by ᴹ✶tārā “lofty” and as such had the alternate meaning “high, sublime”. Thus its gloss “awful” has the sense “causing awe” rather than its modern English meaning “terrible”, and its general meaning seems to something that is mighty (in strength or size) and also induces awe, either inspiring or terrifying. Its Quenya equivalent Q. taura continued to appear in later writings (PE17/115, VT39/10), indicating that this Noldorin word probably remained valid in Sindarin.
Conceptual Development: The Gnomish Lexicon of the 1910s had the adjective G. taura “powerful” and the (archaic) noun G. †taur “ability, power” (GL/69), both based on the early root ᴱ√TURU “am strong” (GL/72; QL/95).
The form dor in the Etymologies is a misreading, see VT/45. In composition and in toponyms, the word is nevertheless reduced to Dor