hieroglyphic (adj.)

1580s, "of the nature of Egyptian monumental writing," from Late Latin hieroglyphicus, from Greek hieroglyphikos "hieroglyphic; of Egyptian writing," from hieros "sacred" (see ire) + glyphē "carving," from glyphein "to carve" (from PIE root *gleubh- "to tear apart, cleave").

Plutarch began the custom of using the adjective (ta hieroglyphika) as a noun in reference to the Egyptian way of writing. The noun use of hieroglyphic in English dates to 1580s (hieroglyphics). Related: Hieroglyphical; hieroglyphically.