Gimilzôr was the Adûnaic name of Elros (SD/380) in the story “The Notion Club Papers” from the mid-1940s. Since the element gimil means “stars”, this name is most likely a translation of the Sindarin name, which means “Star-foam”.
In later writings, Gimilzôr is the son of Ar-Sakalthôr and the 23rd ruler of Númenor, whose Quenya name was Tar-Telemnar (S/268). It is unclear whether this instance of Gimilzôr retains the same meaning as the earlier version of the name. It is possible that the later version has the same meaning as Telemnar (translated by most authors as “Silver-fire”), in which case Tolkien may also have revised the Adûnaic name of Elros (the word for “foam” was elsewhere given as Ad. roth). Alternately, it could be that the Adûnaic and Quenya names are unrelated, and Tar-Telemnar simply adopted the Adûnaic name of his illustrious ancestor.
Andreas Moehn suggested (EotAL/KH-B-L) that if Gimilzôr means “Silver-fire”, its initial element gimil “silver” could be a cognate of Dwarvish kibil. Carl Hostetter and Patrick Wynne suggested (AAD/11) that his Quenya name Telemnar contains adjective ᴹQ. telemna “of silver”, and does not involve “fire” at all.
Conceptual Development: As a name for Eärendil, this name first appeared as Indilzar (SD/363).