Ancient coastal city, Cyrenaica. Located in modern Libya, it received its name in the 3rd century BC from Ptolemy III, who united Cyrenaica with Egypt. Its economy was based on trade with the interior, and it flourished in Hellenistic times, in the early period of the Roman Empire, and again from the late 3rd century AD, when Diocletian made it the metropolis of the Roman province of Upper Libya.

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This adjective is usually used in one of two ways:

• To describe the Egyptian dynasty founded in 305 BC by Ptolemy I Soter
• To describe the writings of Claudius Ptolemaeus, the 2nd century AD geographer and astronomer/astrologer

Common uses include:

• Ptolemaic dynasty
• Ptolemaic Egypt
• Ptolemaic Kingdom
• Ptolemaic period
• Ptolemaic system

Ptolemaic can also refer to other people or objects called Ptolemy, see Ptolemy (name).