three-ply vs trivalent

three-ply

adj

  • Having three strands or layers 

noun

  • Yarn having three strands 

trivalent

adj

  • Having a valence of three. 

  • Protecting against three different (usually flu) viruses. 

noun

  • Any trivalent chromosome 

How often have the words three-ply and trivalent occurred in a corpus of books? (source: Google Ngram Viewer )