ob·so·les·cence 
/ˌɑ:bsəˈlɛsn̩s/ noun
/ˌɑ:bsəˈlɛsn̩s/ noun [noncount] : the condition of no longer being used or useful : the condition of being obsolete
▪ the obsolescence of the old technology ▪ Once a useful tool, slide rules have fallen into obsolescence. ▪ built-in/planned obsolescence [=the practice of making or designing something (such as a car) in such a way that it will only be usable for a short time so that people will have to buy another one]
▪ the obsolescence of the old technology ▪ Once a useful tool, slide rules have fallen into obsolescence. ▪ built-in/planned obsolescence [=the practice of making or designing something (such as a car) in such a way that it will only be usable for a short time so that people will have to buy another one]
