decline vs sour

decline

verb
  • To become weaker or worse. 

  • To choose not to do something; refuse, forbear, refrain. 

  • To run through from first to last; to recite in order as though declining a noun. 

  • To cause to decrease or diminish. 

  • To bend downward; to bring down; to depress; to cause to bend, or fall. 

  • To turn or bend aside; to deviate; to stray; to withdraw. 

  • To move downwards, to fall, to drop. 

  • To inflect for case, number, gender, and the like. 

  • To reject a penalty against the opposing team, usually because the result of accepting it would benefit the non-penalized team less than the preceding play. 

  • To recite all the different declined forms of (a word). 

noun
  • A weakening. 

  • Downward movement, fall. 

  • A reduction or diminution of activity. 

  • The act of declining or refusing something. 

  • A sloping downward, e.g. of a hill or road. 

sour

verb
  • To become sour. 

  • To make sour. 

  • To spoil or mar; to make disenchanted. 

  • To become disenchanted. 

  • To make (soil) cold and unproductive. 

  • To macerate (lime) and render it fit for plaster or mortar. 

  • To process (fabric) after bleaching, using hydrochloric acid or sulphuric acid to wash out the lime. 

noun
  • A drink made with whiskey, lemon or lime juice and sugar. 

  • The acidic solution used in souring fabric. 

  • Any cocktail containing lemon or lime juice. 

  • A sour or acid substance; whatever produces a painful effect. 

  • The sensation of a sour taste. 

adj
  • Having an acidic, sharp or tangy taste. 

  • Unfortunate or unfavorable. 

  • Peevish or bad-tempered. 

  • Off-pitch, out of tune. 

  • Made rancid by fermentation, etc. 

  • Excessively acidic and thus infertile. 

  • Tasting or smelling rancid. 

  • Containing excess sulfur. 

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