Tulkas (Tulkass-, as in dat.sg. Tulkassen) masc. name, used of a Vala, adopted and adapted from Valarin (WJ:399, TULUK)
tulkasmasculine name. Tulkas
Name of the strongest (physically) of the Valar, spouse of Nessa (S/26). His name was an adaption name of his Valarin name Tulukhastāz “Golden-haired” (WJ/399), but it might have been interpreted as a derivative of the adjective (ᴹQ.) tulka “firm, strong, immovable, steadfast” after the original meaning was lost. This is one of the names Tolkien consistently spelled with a “k” (like Kementári and Melkor) despite normally representing the [k]-sound with “c” in Elvish.
Conceptual Development: This name dates back to the earliest Lost Tales (LT1/66), and ᴱQ. Tulkas appeared in the Qenya Lexicon as a derivative of the root ᴱ√TULUKU alongside words meaning “steady, firm” and “to establish” (QL/95, LT1A/Tulkas). This name had essentially the same meaning in The Etymologies from the 1930s, where ᴹQ. Tulkas appeared as an derivative of the same root ᴹ√TULUK, from primitive ᴹ✶Tulkathŏ (Ety/TULUK). The idea that it was an adaptation of a Valarin name did not emerge until the “Quendi and Eldar” essay from 1959-60 (WJ/399).
In The Etymologies, Tolkien gave the (ᴹQ) genitive form of this name as Tulkassen, implying a stem form Tulkass-. This stem form doesn’t same to fit its later derivation from Val. Tulukhastāz, however.