Hieroglyph

A sacred character; a character used in picture writing, as of the ancient Egyptians, Mexicans, etc. Specifically, in the plural, the picture writing of the ancient Egyptian priests. It is made up of three, or, as some say, four classes of characters: first, the hieroglyphic proper, or figurative, in which the representation of the object conveys the idea of the object itself; second, the ideographic, consisting of symbols representing ideas, not sounds, as an ostrich feather is a symbol of truth; third, the phonetic, consisting of symbols employed as syllables of a word, or as letters of the alphabet, having a certain sound, as a hawk represented the vowel a.

Any character or figure which has, or is supposed to have, a hidden or mysterious significance; hence, any unintelligible or illegible character or mark.[Colloq.]