A living language is a dynamic language. It changes and evolves over time to better fit (and boldly go!) the changing and evolving milieu of its speakers. New inventions and concepts need names so that they can be talked about. (Insert video clip of the Dowager Countess of Grantham ingenuously asking, “What is a ‘weekend’?” here) Words also drop out of common usage because people don’t need to talk about those things anymore for whatever reason. (That’s what makes Shakespeare so difficult. Everyday life has changed rather substantially between his time and ours, and many of the words that described everyday life at the turn of the 17th century have dropped out of “common knowledge” over the intervening 400+ years.) (Ask a Millennial why you refer to ending a phone call as “hanging up.” or what “Betamax” is)
One way we make new words for new things is to combine words in new ways (which English inherited from its Germanic roots), like “hatchback” and “skateboard.” “History bounding” describes the practice of recreating and adapting garments from a particular historical period to make them part of your everyday wardrobe. CosTubers (Costume+YouTube) have whole channels devoted to the practice. This is not to be confused with “Cosplay,” (costume+play), which is the hobby of recreating the costume of a character in film, television or print to wear for fun, or “-core” where a person incorporates aspects of their “core interest” into their daily life (cottagecore, medievalcore, bardcore, etc.). We now have “spheres” or the concepts, practices, and participants to do with a particular interest or activity (the blogsphere, the Twittersphere), and “-verses” — the “fictional universe” in which a particular film, book, or TV series is set (the Potterverse, the Duneverse, the Whoniverse, etc.)
The meanings of words can change over time. A case in point is the word “terrific,” which literally means “causing terror.” It has acquired the additional meanings of “great size, amount or intensity,” and is now used as an exclamation of approval. Terrific! One has only to listen to a Millennial or GenZ to appreciate that the words “sick” and “stupid” have also acquired additional meanings beyond the literal, as has the word “awesome.” (If a Millennial describes your child as “stupid cute,” that is a high compliment.) In addition to its literal meaning, “gnarly” has acquired two other meanings that are exact opposites: awesome and excellent versus gruesome and unpleasant.
Words become streamlined, like “app” (from “application”) and “phone” (from “telephone”). A “fanatic” has been a “fan” for quite a while, but now they congregate at “cons” (from “convention”), buy “merch” (“merchandise”) and there is typically cosplay involved. “High resolution” becomes “hi res” and “low fidelity” becomes “lo fi.” Some phrases get stripped right down to acronyms. “By the way,” becomes BTW, “laugh out loud” becomes LOL, and “in my humble opinion” becomes IMHO. We used to have a US President; now we have a POTUS.
How we use words changes, too. Not so long ago, “extinction” was a state of being. The dinosaurs became extinct. They were no more. Now it’s a destination (“the point of no return”) as more and more species go extinct. We’re doers now. Scientist do science. Mathematicians don’t analyse things mathematically anymore, they do math to it. Pregnancy went from a state of being (you either are or you aren’t) — “she became pregnant,” to something you caught like a disease — “she got pregnant” to the result of encountering a trip hazard — “she fell pregnant.” We used to “set foot” (A virgin forest is where the hand of Man has never set foot.) Now we “step foot” — which has a certain logic to it, I suppose, but not quite the same ring.