Is there such a thing as a synonym? I seem to remember a character in Tom Robbins’ Jitterbug Perfume arguing passionately that there is not, that each word in English has its own distinct meaning and proper usage. I wouldn’t go that far, but I do think that the beauty of English, as big and messy as it is, lies in having so many options and striving to choose exactly the right one for what you want to express.
For example, I hear annihilate and decimate used interchangeably, but they actually have substantially different meanings. Annihilate has the Latin root nihil (“nothing”) while decimate has the Latin root decimus (“tenth”). So to annihilate something is to reduce it to nothing; to decimate is to reduce either by 10% or to 10% of the original amount, depending on how much of a stickler one wants to be to the original meaning. The term originates in the Roman practice of punishing mutineers by killing one in ten among their ranks, but I’ve almost always heard it used to mean “to reduce by a significant amount.” It’s been used that way since the 1600s, and it’s in the OED, so it’s fine by me.
In any case, one can decimate an army, or a town, or a pie, but not, strictly speaking, an opponent at Scrabble. Though maybe one could decimate an opponent’s pride?
We have so many ways to express different shades of destruction. Destroy in fact has a sense of building in its root (Latin struo, struere, struxi, structus: “to put together, pile up, build”), like its antonym construct. Demolish has this sense, too, from Latin molior, moliri: “to build, erect, work at.” The de- prefix is just motion downwards.
Obliterate contains the Latin word littera (“letter”), giving it a literal meaning (ha!) of something like “against the letters” (the ob- prefix is often difficult to render into English), hence “to blot out, wipe out, or cancel,” as one would debts, and from there “to destroy” in the sense of “to erase from memory.” Our delete has the same root and similar original meaning.
Terminate comes from Latin terminus (“limit, boundary”), like our terminal, term, and determine, and means something like “to bring to an end.” I think The Terminator is a fitting name for that Arnold Schwarzenegger character because it contains a sense of fate more than The Destroyer or The Annihilator would.
Exterminate, by contrast, originally meant “to drive beyond the boundaries” or “to banish.” But that ex- prefix can also just mean “completely,” and I think exterminators would prefer that we think of them as finishing pests off entirely rather than just herding them out of the yard.
Eliminate has a similar original sense. Limen is Latin for “threshold” (you can see it in subliminal as well), so “to eliminate” was originally “to carry/thrust out of doors,” thus the modern definitions “to expel from the body,” and “to get rid of.”
Eradicate is probably my favorite of these. Latin radix means “root” (as in radical and radish), so “to eradicate” is “to root out” or “to pull up from the roots.”
Extinguish and extinct are both from Latin stinguere, “to quench,” which I think is probably related to tingere, “to moisten.”
Execute literally means “to follow out” (Latin sequor, sequi: “to follow”). One’s executioner and the executor of one’s estate serve very different functions yet share a similarity in the root meaning of their title.
If we’re looking for a true synonym of annihilate, devastate is perhaps the closest we can get based on the roots of the words. Latin vastus means “empty, desolate, ravaged, vast.” But then again, even though both words essentially mean “to reduce to nothing/emptiness,” we do use them in subtly different ways. We might say that someone was devastated after a break up, but not annihilated.
My point in all of this is not to suggest that you’ve been using these words incorrectly all along, nor that there is one standard meaning for each word that every person must adhere to. English is lovely because it is such a mess, and people should feel free to play with it as they please. I think knowing where words come from and what they originally meant (even– or especially– if they’ve drifted pretty far from that meaning) is one of the most enjoyable aspects of being an English-speaker.
I think it’s also worth considering why we have so many different ways in English to express the concept of “destruction.” What does that say about us?