selcouth

Strange; unfamiliar; marvellous. Combining the sense of strangeness with that of wonder, selcouth is a fantastic self-referential word, being both marvellous and (to most English speakers) entirely unfamiliar. No word is really synonymous with it, and it reflects very well the sense of wonder and amazement at seeing something truly new and unusual. (From The Phrontistery)

Literally, 'seldom known'! Has a lovely old english sound to it!