It's spelled Eärendel, and it's from an Anglo-Saxon poem by the poet Cynewulf, where it refers to the Morning
Star (in the context of the poem, the Morning
Star is in itself a reference to
John the
Baptist).
Tolkien used it (spelled Eärendil) as a part of his mythology. His character Eärendil is identified with
Christ by Tolkien scholars.
As a name I'm not too fond of it - the 'Ear' at the start is off-putting and it's just a little too weird. Middle name at the most!