The fact is, language is and always has been very fluid. It is constantly changing. I have become more aware of this recently while reading World Histories and Mysteries, by the editors of the American Heritage Dictionary. This books explains in detail the etymologies of hundreds of English words, "from ABACADABRA to ZEUS," as the subtitle says. The elaborate histories of words and their changes is astounding. It is surprising we can understand people who wrote 100 years ago.
Did you know that the "bel-" in "belfry" has nothing to do with the English word "bell?" and that a belfry wasn't always a bell tower?
Did you know that the word "sky" used to mean "cloud" at the same time as the word "cloud" meant "hill?"
Did you know that the word "mutt" was first used to refer to a dog in 1906, and that it comes from an insult that means "stupid person," = muttonhead?
Did you know that the word "dress" is related to the word "direct?" Or that the word "Ciao!" is related to the word "slave?"