trefoil vs triune

trefoil

noun
  • Any of several plants of the pea family, having compound, trifoliate leaves; especially one of the genus Trifolium. 

  • A symbol having the shape of such leaves, especially when used as an architectural ornament. 

triune

adj
  • Both three and one at the same time. 

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