hieroglyphic vs ideogram

hieroglyphic

noun
  • Any symbol used in this system; a hieroglyph. 

  • Undecipherable handwriting or secret symbol. 

  • A writing system of ancient Egypt, Minoans, Maya and other civilizations, using pictorial symbols to represent individual sounds as a rebus 

adj
  • difficult to decipher 

  • of, relating to, or written with this system of symbols 

ideogram

noun
  • A picture or symbol which represents the idea of something without indicating the sequence of sounds used to pronounce it. Examples include digits, traffic signs, and graphic symbols such as @. 

How often have the words hieroglyphic and ideogram occurred in a corpus of books? (source: Google Ngram Viewer )