A group of ravens can be referred to as an unkindness, a rave, a conspiracy, a treachery, or a flock. The term "unkindness" may have originated from the misguided belief in the 19th century that ravens were not caring parents and would sometimes expel their young from their nests before they were ready to fend for themselves. However, the term "unkindness" may also be related to the negative connotations associated with ravens in mythology, where they were often associated with bad luck and trickery. Other birds also have unique collective nouns, such as a murder of crows and a murmuration of starlings.