No, I don't know anything about obscure jargon used by tollbooth personnel, or anything like that. (Sorry, Georgette Heyer fans.) I'm talking about those who see themselves as guardians of proper English. Gatekeepers include English teachers and professors, editors of various sorts, and many amateurs who offer corrections for love of the language.
As an editor some years back, I felt guilty for using "tidal wave" in a headline instead of "tsunami" -- I wasn't sure about the reading level of my audience, but shouldn't I have given them the benefit of the doubt? I felt a little better after finding out that the Japanese word's roots simply mean "harbor wave," which isn't any more accurate in describing the phenomenon. Scientists prefer tsunami, but most people understand that "tidal wave" refers not to neaps or ebbs or other types of gravity-based water movements, but to the walls of water caused by earthquakes.
English is a constantly evolving language, with users borrowing from others, creating new words, and using old ones in new ways. (The whole plot of the wonderful 1941 comedy "Ball of Fire" gets started by Gary Cooper's realization that he's falling behind in his attempt to list and define slang expressions for an encyclopedia.)
Language lovers face constant conflicts between purism and popular usage, and like actual battles, experts love to keep rehashing old ones. A recent NPR commentary reviews a new book, "The Story of Ain't," about the cultural upheaval caused in 1961 by Merriam's publication of the third edition of Webster's International Dictionary.
I wasn't born yet when that controversy arose, but I know something about it because of my reading habits. Rex Stout's 1962 murder mystery, "Gambit," features a scene where detective Nero Wolfe is ripping out pages from that dictionary and burning them. Before he consents to take on a new client, the linguiphile asks her whether she uses "infer" and imply" interchangeably.
Wolfe, Miss Blount, and I (and probably Stout) all agree that the answer to this should be "No!" To infer is to deduce a conclusion from available facts or statements, and to imply is to arrange statements in a way that suggests a conclusion. (Suppose I say that Jane's failing store burned down the day after she took out extra insurance; I'm probably implying that police should check for accelerants, and you may infer that I think arson is a possibility.) Saying that "infer" may be used in place of "imply" creates ambiguity and undermines the value of both words.
However, aside from condoning conflation of distinct words, Webster's third edition drew a great deal of criticism for its inclusion of colloquialisms including "litterbug." Here, I am in favor of modernizing language. New words are needed to label new technologies, new cultural practices, and new times in general. Few people these days object when dictionaries add new words; Merriam-Webster and the Oxford English Dictionary, among others, invite publicity when they release lists of new words.
For me, the question to be asked in evaluating word usage is whether it eases or hinders communication. If a new word, or a new use of a word, helps clarify meanings, then I'm all for it. If it muddies the waters, well, I wouldn't burn a whole dictionary over it, but I would definitely call it out as a mistake.