The 18th ruler of Númenor, whose Quenya name was Tar-Calmacil “Light-sword” (UT/222). If his Adûnaic and Quenya names have the same meaning, the second element zagar of his name most likely means “sword”. The first element might mean “light”, as suggested by Andreas Moehn (EotAL/BAY’L), but the element bel- is attested elsewhere as a verbal element meaning “to love”. It is possible the two meanings coexisted, or that Tolkien changed the meaning of bel* from “love” to “light”.
This name violates the original phonetic rules of Adûnaic, which said that the vowels [ē] and [ō] could only be long in Adûnaic (SD/423). See the discuss of conceptual-changes-in-late-Adûnaic for more information.