Words have lives, too

Just like us, words have lives. They are born, they struggle for survival and eventually they die.

Words have to come from somewhere. They are born when a new word is coined. 

Words might need to compete with other words for survival. For example, you could say 'maybe' or you could say 'perhaps'. I think you would agree that the word 'maybe' is more popular. Everyone seems to say 'maybe', but only a few people use 'perhaps'. As a word becomes less popular, it could begin to sound old-fashioned and it's decline is hastened. Eventually, nobody uses it anymore and the word is 'dead'.

The Darwinian-style life struggle of a word is influenced by coevolutionary social, technological, and political factors (see this link for empirical research).

A word most often lives longer than we do. A word can live for a few hundred years or more. Many Latin words have even outlived the death of their own language and live on in other host languages to this day, in phrases like alma mater.  

I'm trying to think of some words which are currently in their death throes and what comes to mind are the words used to describe groups of animals. After all, when was the last time you heard someone talking about a clowder of cats?