Valaróma
The Great Horn of Oromë.
Rombaras. ( Earlier name. Rejected in the revision of Ainulindalë 1951 )
The horn would be heard above all other horns, the sound was like the upgoing of the Sun or the sheer lightning cleaving the clouds. The sound of Valaróma ringed between the mountains and echoed through the valleys. This indeed was a mighty horn that would scare all evils away and even Melkor would hide in Utumno as the horn foreboded the wrath of Oromë. Only once does the tale tells of Valaróma failing and that was when Ungoliant belched forth her black vapours in the assault upon the two Trees Laurelin and Telperion.
The early name Rombaras ( See also Falarombar, the horns of Ulmo too ) derives from the stem Rom=loud noise, horn-blast. Quenya: Romba=horn,trumpet. The second may be from Barás-[only found in Noldorin]:fiery or eager or from the stem Ras-:stick up or in Quenya: rasse=horn, especially on animals.
Related Links.: Encyc.: Valaróma.