fixity vs uncertainty

fixity

noun
  • The position of an operator relative to its operand (prefix, postfix) or operands (infix). 

  • Something fixed. 

  • The state or condition of being fixed. 

uncertainty

noun
  • Doubt; the condition of being uncertain or without conviction. 

  • A parameter that measures the dispersion of a range of measured values. 

  • Something uncertain or ambiguous. 

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