contiguity vs synapse

contiguity

noun
  • A state in which two or more physical objects are physically touching one another or in which sections of a plane border on one another. 

synapse

noun
  • The junction between the terminal of a neuron and either another neuron or a muscle or gland cell, over which nerve impulses pass. 

verb
  • To form a synapse. 

  • To undergo synapsis. 

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