obsolescence

Etymology

From Latin obsolescens past participle of obsolescere.

noun

1. (uncountable) The state of being obsolete—no longer in use; gone into disuse; disused or neglected.
   Apart from this feature the Trichoptera also differ from the typical Neuroptera in the relatively simple, mostly longitudinal neuration of the wings, the absence or obsolescence of the mandibles and the semi-haustellate nature of the rest of the mouth-parts. 1911, “Caddis-fly and Caddis-worm”, in 1911 Encyclopædia Britannica
   One way is to legislate extended warranties on products, so washing machines and refrigerators last for 30 years instead of 10. Another is to ban planned obsolescence, so manufacturers can’t create products that are designed to fail. 2019, Jason Hickel, “Climate breakdown is coming. The UK needs a Greener New Deal”, in Guardian.
2. (countable) The process of becoming obsolete, outmoded or out of date.
   Shared obsolescences can be of some significance when connected with a functional replacement. If two languages replace an earlier word for 'nose' with some other term and also lose the traditional term, this double agreement is of significance for judging the existence of a common historical period. 2005, Joseph Harold Greenberg, William Croft, Genetic Linguistics