hi·er·o·glyph·ic / ˌhī(ə)rəˈglifik/ • n. (hieroglyphics) writing consisting of hieroglyphs. ∎  enigmatic or incomprehensible symbols or writing: tattered notebooks filled with illegible hieroglyphics.• adj. of or written in hieroglyphs. ∎  (esp. in art) stylized, symbolic, or enigmatic in effect.DERIVATIVES: hi·er·o·glyph·i·cal adj.hi·er·o·glyph·i·cal·ly adv.

hieroglyphics Writing system used in ancient Egypt and, by extension, those of ancient Crete, Asia Minor, Central America and Mexico. The Egyptian system of hieroglyphics (pictorial characters) arose sometime before 3100 bc. At first they were purely picture symbols. The word ‘sun’ was represented by a circle with a dot inside. In due course, they also came to be used conceptually, with symbols such as that for ‘sun’ also standing for ‘day’. Eventually, many symbols were used phonetically. The ‘sun’ symbol, for instance, stood for a syllable that contained the same combination of consonants but had a different meaning. By the 7th century, hieroglyphics were used for business and literary purposes. As ancient Egyptian was supplanted by Greek, hieroglyphics died out. Most Egyptian texts have been deciphered, thanks to the discovery of the Rosetta Stone (1799).

Hieroglyphs

This term, normally applied to ancient Egyptian picture writing, is also used for the symbolic illustrations in astrological almanacs and for symbols produced by automatic and direct writing through mediumship. Direct writing (i.e., messages produced without contact between mediums and writing materials), although sometimes produced at séances, has also occurred during outbreaks of poltergeist phenomena, when the poltergeist distributes messages throughout a house. For example, in a disturbance in the house of Eliakim Phelps, in Stratford, Connecticut (1850-51), hieroglyphs were found on the walls and ceilings. The matter was investigated by Spiritualist medium Andrew Jackson Davis, who claimed to recognize the hieroglyphs as spiritual symbols. He interpreted them as friendly messages from spiritual powers.

Sources:

Capron, E. W. Modern Spiritualism: Its Facts and Fanaticisms. Boston: B. Marsh; New York: Patridge and Brittan, 1855.

hieroglyphic pertaining to ancient Egyptian writing; sb. character in such picture-writing; symbolic or enigmatic figure. XVI. — F. hiéroglyphique or late L. hieroglyphicus — Gr. hierogluphikós, f. hierós sacred + gluphġ carving.
Hence, as back-formation or after F. hiéroglyphe, hieroglyph XVII.