difficult to decipher
of, relating to, or written with this system of symbols
Undecipherable handwriting or secret symbol.
Any symbol used in this system; a hieroglyph.
A writing system of ancient Egypt, Minoans, Maya and other civilizations, using pictorial symbols to represent individual sounds as a rebus
Hard to grasp; not obvious or easily understood.
Tenuous; rarefied; of low density or thin consistency.
Barely noticeable, not obvious, indistinct.
Cleverly contrived.
Cunning, skillful.
Insidious.