Uldor the Accursed

We have partial interpretation of Uldor's name, in that the first element Ul- was said to derive from ulgu, meaning 'hideous' or 'monstrous'. The second element -dor is unexplained; in Elvish it would most commonly mean 'settle, remain' (or by extension 'land') but these meanings do not seem to easily fit Uldor. It should be noted that Uldor was a name given to this traitor after the fact by the Elves; he would originally have had a quite different name in his own tongue, but that original name is not recorded.