surd vs tongue-tied

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. 

tongue-tied

adj
  • Prevented from or unable to express oneself clearly or fluently, or freely; at a loss for words, speechless. 

  • Reluctant to speak up; reserved, reticent. 

  • Having tongue-tie or ankyloglossia (“a congenital oral anomaly in which the lingual frenulum (a membrane connecting the underside of the tongue to the floor of the mouth) is unusually short and thick, decreasing mobility of the tongue and affecting eating, speech, etc.”). 

  • Physically unable to speak; dumb, mute. 

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