This week it’s susurrus (noun) a soft murmuring or rustling sound. Whisper.
From Latin susurrare (to whisper or hum). May also be used in Late Middle English according to http://www.memidex.com/susurrus#etymology
I can’t remember my first discovery of this word, but I know that since I have come across it in Terry Pratchett’s Tiffany Aching novels. I felt validated (because I’m that insecure) when the heroine used it and remarked that it means what it sounds like. It so does! go on, say it a couple of times and feel it slip over the front of your tongue.