ob ‧ so ‧ les ‧ cence /ˌɒbsəˈles ə ns $ ˌɑːb-/ BrE AmE noun [uncountable]
1 . when something becomes old-fashioned and no longer useful, because something newer and better has been invented
2 . planned/built-in obsolescence when a product is designed so that it will soon become unfashionable or impossible to use and will need replacing:
the planned obsolescence of some software