decay vs wane

decay

verb
  • To deteriorate, to get worse, to lose strength or health, to decline in quality. 

  • To undergo bit rot, that is, gradual degradation. 

  • To undergo optical decay, that is, to relax to a less excited state, usually by emitting a photon or phonon. 

  • Loss of airspeed due to drag. 

  • To undergo software rot, that is, to fail to be updated in a changing environment, so as to eventually become legacy or obsolete. 

  • To change by undergoing fission, by emitting radiation, or by capturing or losing one or more electrons; to undergo radioactive decay. 

  • To cause to rot or deteriorate. 

  • Of an array: to lose its type and dimensions and be reduced to a pointer, for example when passed to a function. 

  • To rot, to go bad. 

  • To undergo prolonged reduction in altitude (above the orbited body). 

noun
  • The process or result of being gradually decomposed. 

  • A deterioration of condition; loss of status or fortune. 

  • The situation, in programming languages such as C, where an array loses its type and dimensions and is reduced to a pointer, for example by passing it to a function. 

wane

verb
  • To progressively lose its splendor, value, ardor, power, intensity etc.; to decline. 

  • Said of light that dims or diminishes in strength. 

  • Said of a time period that comes to an end. 

  • Said of the Moon as it passes through the phases of its monthly cycle where its surface is less and less visible. 

noun
  • A gradual diminution in power, value, intensity etc. 

  • The end of a period. 

  • The lunar phase during which the sun seems to illuminate less of the moon as its sunlit area becomes progressively smaller as visible from Earth. 

  • A child. 

  • A rounded corner caused by lack of wood, often showing bark. 

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