Burárum

A sound or word issued by Treebeard when he spoke of the Orcs. Its meaning is not known with certainty, and it may even be a part of the Entish word for 'Orcs'. More likely, though, it represents a 'deep rumbling noise like a discord on a great organ'¹, signifying Treebeard's disgust at the thought of these creatures.

Though we don't know the actual Entish word for 'Orcs' (assuming it isn't burárum), we do have a segment of it translated into English: 'evileyed-blackhanded-bowlegged-flinthearted-clawfingered-foulbellied-bloodthirsty'², and also some fragments of this in Elvish: morimaite ('blackhanded') and sincahonda ('flinthearted').