hieroglyphic

noun

1. (in-plural)A writing system of ancient Egypt, Minoans, Maya and other civilizations, using pictorial symbols to represent individual sounds, often as a rebus.
2. Any symbol used in this system; a hieroglyph.

   “I must say, that, at the coronation, there was little vestige left as possible "of the charms that pleased a king." "She looked," Lady Mary Wortley said, "like an Egyptian mummy, wrought with hieroglyphics of gold."”

   “The hieroglyphics or symbols, however, were reversed, just as though they had been pressed on wax.”

3. (broadly)Undecipherable handwriting or secret symbol.

   “Above all, the 48-page timetables of the new service, which have been distributed free at every station in the scheme, are a model to the rest of B.R. For the first time on British Railways, so far as we are aware, a substantial timetable has been produced, not only without a single footnote but also devoid of all wearisome asterisks, stars, letter suffixes and other hieroglyphics.”

adj

1. Of, relating to, or written with such a system of symbols.

   “the hieroglyphic writing of ancient Egypt”

   “a hieroglyphic obelisk”

   “'Is there any meaning, do you think?' 'That little arrangement comes in more than once,' said Elsie, indicating a hieroglyphic twist. 'I'm sure it must mean something.'”

2. Difficult to decipher.