Unkindness

His unkindness made her angry.

His unkindness made them angry.

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.