interminable vs surd

interminable

adj
  • Existing or occurring without interruption or end; ceaseless, unending. 

surd

adj
  • unvoiced; voiceless 

  • Involving surds, or irrational numbers; not capable of being expressed in rational numbers. 

noun
  • An irrational number, especially one expressed using the √ symbol. 

  • A voiceless consonant. 

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