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.
in the names of sciences or disciplines (acoustics, aerobics, economics, etc.), a 16c. revival of the classical custom of using the neuter plural of adjectives with Greek -ikos "pertaining to" (see -ic) to mean "matters relevant to" and also as the titles of treatises about them. Subject matters that acquired their English names before c. 1500, however, tend to be singular in form (arithmetic, logic, magic, music, rhetoric). The grammatical number of words in -ics (mathematics is/mathematics are) is a confused question.
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Harper, D. (n.d.). Etymology of hieroglyphics. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/hieroglyphics