I thought as I received notable words from Wordnik's Word of the Day service, I'd post them here. If you like, sign-up for Wordnik's Word of the Day service yourself.
rusalka
In Russian folk-lore, a water-nymph.
The rusalki were thought to be most dangerous during Rusalka Week in early June, when they were supposed to leave the water to swing on tree branches at night.