servile vs surd

servile

adj
  • Not sounded, but serving to lengthen the preceding vowel, like the e in tune. 

  • Of or pertaining to a slave. 

  • Not belonging to the original root. 

  • Slavish or submissive. 

noun
  • A slave; a menial. 

  • An element which forms no part of the original root. 

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 servile and surd occurred in a corpus of books? (source: Google Ngram Viewer )