A sobriquet adopted by Túrin in defiance of the curse set upon him by Morgoth translated “Master of Doom” (S/217). The first element of this name is tur “master”. The second element resembles the variant form ambar of umbar seen in the phrase a Túrin Turambar turún’ ambartanen “O master of doom by doom mastered”. Elsewhere, however, Tolkien stated that the second element was derived directly from the primitive form ✶ṃbart(ă), with the middle vowel a originally associated with the verbal element tur-: ✶tura-mbar (PE17/104, 124).
Conceptual Development: This name dates back to the earliest Lost Tales (LT2/70). The name ᴱQ. Turambar appeared in the Qenya Lexicon beside a variant form Turamarto (QL/95), but in all the narratives it consistently appeared as Turambar. At the earliest stage, this name was likely a compound of the root ᴱ√TURU (LT1A/Meril-i-Turinqi, QL/95) and ᴱQ. ambar “fate” (LTA2/Turambar, QL/34).
In The Etymologies from the 1930s, ᴹQ. Turambar appeared as a derivative of the roots ᴹ√TUR and ᴹ√MBARAT (Ety/TUR, MBARAT), but Tolkien revised the Quenya word for “fate” to ᴹQ. umbar, so that it could no longer be a direct element of this name. Tolkien considered but rejected a new form ᴹQ. Turumbar (Ety/TUR). Hereafter, Tolkien probably considered the name to be an older compound assembled from its primitive elements.
Tolkien did gradually alter the translation of this name, from ᴱQ. “Conqueror of Fate” (LT2/86) >> ᴹQ. “Master of Fate” (Ety/TUR) >> Q. “Master of Doom” (S/217).
Turambar masc. name, "Master of Doom/Fate", name taken in pride by Túrin (Appendix A, SA:tur, TUR, MBARAT, VT49:42)