hyaloid vs perspicuous

hyaloid

adj
  • transparent or glassy 

noun
  • The hyaloid membrane 

perspicuous

adj
  • Transparent; translucent. 

  • (Of a language or notation) the process of inference from premises to conclusion is explicitly laid out. 

  • Clearly expressed, easy to understand; lucid. 

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