unkindness

ilkeys, tylyys, kalseus puhekieltä The state or quality of being unkind.
puhekieltä An unkind act.
puhekieltä The collective noun for raven ravens
2006, Kate Forsyth, The Shining City: Book Two of Rhiannons Ride'', Roc (2006), ISBN 9781101043530, http://books.google.com/books?id=VkpZvk-PNn8C&pg=PT12&v=onepage&q&f=false unnumbered page:

All Olwynne could remember, though, was her father falling away from her into some deep pit, his black wings bent over his face, and then hundreds of ravens, an unkindness of ravens, plummeting from the sky to peck out her eyes.

"There's an unkindness of ravens that roosts on top of the guild. Their numbers are growing by the day. Aren't they spectacular?

A raven cawed somewhere up ahead, and its cry was answered by others, an unkindness of ravens on all sides.