acquiescence vs niggle

acquiescence

noun
  • Inaction, passivity, or neglect to take legal action when it is called for in order to assert, preserve, or safeguard a right, and which inaction implies the abandonment of said right. 

  • A silent or passive assent or submission, or a submission with apparent content, distinguished from avowed consent on the one hand, and on the other, from opposition or open discontent; quiet satisfaction. 

niggle

noun
  • A minor complaint or problem. 

verb
  • To use, spend, or do in a petty or trifling manner. 

  • To dwell too much on minor points or on trifling details. 

  • To fidget, fiddle, be restless. 

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