Cassiopeia

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A W-shaped constellation in the Northern Hemisphere between Andromeda and Cepheus.

Century Dictionary and Cyclopedia

1. n. A beautiful circumpolar constellation, supposed to represent the wife of Cepheus seated in a chair and holding up both arms. It contains 30 stars brighter than the sixth magnitude, and is always found opposite the Great Bear on the other side of the pole-star. In this constellation appeared in 1572 a temporary star brighter than Venus at its brightest.
2. n. [NL.] In zoology, the typical genus of the family Cassiopeiidæ. C. borbonica of the Mediterranean is an example. C. frondosa inhabits the Florida keys. Originally Cassiopea. Pėron and Lesson, 1809.

Wiktionary

1. n. Greek mythology Proud wife of Cepheus and mother of Andromeda, queen of Eritrea. When she boasted that her beauty was equal to that of the Nereids, she was punished by Poseidon.
2. n. astronomy A circumpolar constellation of the northern sky representing Queen Cassiopeia from Greek myth. The constellation lies between Cepheus and Perseus.

GNU Webster's 1913

1. n. (Astron.) A constellation of the northern hemisphere, situated between Cepheus and Perseus; -- so called in honor of the wife of Cepheus, a fabulous king of Ethiopia.

WordNet 3.0

1. n. (Greek mythology) the wife of Cepheus and mother of Andromeda
2. n. a W-shaped constellation in the northern hemisphere near Polaris