The term Egyptian referred to people, culture, language, and objects originating from the Earth country of Egypt.
The Rosetta Stone was a key discovery in Human archaeologists being able to decipher Egyptian hieroglyphs. (DIS: "Rosetta")
In 2270, James T. Kirk noted that structures in Kukulkan's city resembled the obelisks built by the ancient Egyptians. Walking Bear disagreed partially, saying the carvings were not Egyptian in origin. (TAS: "How Sharper Than a Serpent's Tooth")