surd vs untoward

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. 

untoward

adj
  • Unseemly, improper. 

  • Unruly, troublesome; not easily guided. 

  • Unfavourable, adverse, or disadvantageous. 

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