1. Alexandrian astronomer (of the 2nd century) who proposed a geocentric system of astronomy that was undisputed until the late Renaissance • Syn: Claudius Ptolemaeus • Derivationally related forms: Ptolemaic • Instance Hypernyms: astronomer, uranologist, stargazer 2. an ancient dynasty of Macedonian kings who ruled Egypt from 323 BC to 30 BC; founded by Ptolemy I and ended with Cleopatra • Syn: Ptolemaic dynasty • Hypernyms: dynasty • Member Meronyms: Ptolemy I, Ptolemy II