fathomless vs surd

fathomless

adj
  • unfathomable or incomprehensible. 

  • Very deep (especially of water deeper than a lead line can measure); bottomless. 

surd

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

  • unvoiced; voiceless 

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

  • A voiceless consonant. 

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