disuse
A state of something not being used for a long time.
Disuse means the state of not being used anymore. When something falls into disuse, people have stopped using it, often gradually over time. An old playground might fall into disuse when a newer one opens nearby. A word can fall into disuse when people stop saying it and choose different words instead.
Disuse is different from something being temporarily unused. Your bicycle sitting in the garage for a week isn't in disuse, but if it sits there untouched for years, gathering dust and rust, then it has fallen into disuse. The key is the sense of abandonment or neglect over a longer period.
Things fall into disuse for many reasons. A hiking trail might become overgrown from disuse when people find a better route. Old factories fall into disuse when companies close or move. Sometimes useful things fall into disuse simply because newer, more convenient options appear. The printing press didn't fall into disuse because it stopped working, but because digital technology came along.
When something is in disuse, it's not necessarily broken or useless. It just isn't being used anymore, often sitting idle while the world moves on to something else.