Oiolossë
From Tolkien Gateway
A name for the mountain of Taniquetil in the Pelóri, on which stood the high halls of Manwë and Varda. Oiolossë was the highest peak in the World, and was always covered with shining snow (hence the name Oiolossë, which means 'everlasting whiteness' or, more literally, 'Ever-snow-white'). The Sindarin version of this name, with the same meaning, was Amon Uilos. There is in fact some confusion over the term Oiolossë. In most sources, it is simply used as another name for the great mountain Taniquetil, but in Valaquenta, it seems to refer specifically to Taniquetil's uttermost snow-covered peak. This subtle shift suggests that its meaning may have changed slightly at some time in the name's history.