They develop in a variety of ways. There is the language of politics, of a trade or profession. We refer to the jargon of sports, of the computer world, of the library profession. Words pass in and out of use. Sometimes these queries can be solved, but at other times they seem to defy solving.
Words demand documenting.
Literary writers dot their works with allusions, names, and terms that earnest students and librarians must puzzle out. So we have the monumental Oxford English Dictionary with its tracking of terms through time, complete with quoted sources documenting the etymology. There are other smaller, more specialized volumes. This curiosity about words, phrases, and expressions goes back long years. One of the more interesting special journals is the English publication Notes and Queries , which began publishing in 1849.