The name of the constellation Orion (LotR/1113). The initial element of this name is telumë “roof, canopy” = “sky” (WJ/411). The second element might be mehtar “warrior” (a possible late variant of ᴹQ. mahtar; see QQ/mehtar), but I think it could instead be ohtar “warrior”.

Conceptual Development: In the earliest Lost Tales, this name appeared as ᴱQ. Telimektar “Swordsman of Heaven”, the son of Tulkas who would become Orion (LT1/101, 200). At this stage, the first element of this name was ᴱQ. telimbo “canopy; sky” (QL/90). Christopher Tolkien suggested its second element may be an otherwise unattested ᴱQ. mektar derived from the root ᴱ√MAKA¹ “slay” (LT1A/Telimektar), but I think it is likelier that the second element was the attested ᴱQ. ektar¹ “swordsman” (QL/35).

In The Etymologies from the 1930s, this name appeared as ᴹQ. Telumehtar “Warrior of the Sky” (Ety/TEL). At this stage, its initial element was ᴹQ. telume “dome of heaven”, and its final element might be ᴹQ. mahtar “warrior” from ᴹ√MAK “sword; fight (with a sword), cleave” (Ety/MAK), though it could have been just a remnant of the Early Qenya form of the name.

The later meaning of the root √MAK shifted so that it meant either “cut, hew with a sharp edge” (VT39/11) or “forge metal” (VT41/10). The form mahtar “warrior” does not appear in later writing; it seems to have been replaced by macar “swordsman; †forger” (VT39/11, VT41/10). In later writings, the word for “warrior” seems to be ohtar (UT/282), which might be the second element in the later form of this name. However, it may be that Tolkien simply copied forward the older name without working out (or writing down) a proper etymology for it.