grapheme vs hieroglyph

grapheme

noun
  • A fundamental unit of a writing system, corresponding to (for example) letters in the English alphabet or jamo in Korean Hangeul. 

  • In alphabetic writing, the shortest group of letters composing a phoneme. 

hieroglyph

noun
  • An element of an ideographic (hieroglyphic) writing system. 

  • Any obscure or baffling symbol. 

verb
  • To represent by hieroglyphs. 

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