Whispering; a whispering noise, as of leaves moved by the wind
From a Greek word that I can't paste into LJ because it doesn't like the funny letters - gosh, why do I keep picking Greek? - meaning 'to whisper.'
1872 M. Collins Pr. Clarice II. xix. 218
Psithurism of multitudinous leaves made ghostly music
Psithurism does not sound like a beautiful word, or as though it would describe a lovely thing, but even a pessimistic crank like me can't resist the psithurism of Autumnal leaves.