Is Macbeth's phrase "terrible feat" an oxymoron?

I had read somewhere that Macbeth’s phrase to describe his impending murder of Duncan as a “terrible feat” was an oxymoron? I don’t see it that way but if it is can someone explain why?

It’s an oxymoron only in the current sense of “terrible,” meaning “very, very bad.” In WIllie’s day, it usually meant something more like “capable of inducing terror,” so, no.

Yeah, it’s probably also true that ‘terror’ has changed a bit too - and would have meant ‘intense and involuntary shocked awe’ or something, rather than the modern pants-wetting-fright, so ‘terrible’ would have been somewhat synonymous with ‘awesome’ in the day.

So I suppose it could be self-contradictory in the sense that it was a planned event, but he was using a word that denotes (at least an element of) surprise.

Or, as Terry Pratchett put it;

If terror is terrible or terrifying what emotion does a “feat” evoke?

I don’t get the contradiction between terrible and feat.

In the sense that “feat” is usually parsed as some sort of positively impressive accomplishment.

For example, you probably wouldn’t casually describe al-Qaeda’s destruction of the World Trade Center towers as a feat, unless you had some provocative purpose for doing so.

Hence, linking the word “terrible,” with its (largely modern, as discussed) negative connotations, and the word “feat,” which suggests a laudable achievement, can be argued as being contradictory.

I don’t know that I buy it, considering how Shakespeare used language in his day, but that’s what’s being suggested.

Perhaps it is something like an ‘appalling triumph’, which would be an oxymoron.

That’s Shakespearean “awesome” and not current day “awesome!”, right?

Something can qualify as an “amazing feat” and yet be inherently bad. If I could somehow travel to eastern Europe, procure a nuclear device from the old Soviet Union that was stolen and put on the Black Market, somehow smuggle it into the United States, and then somehow smuggle it into the basement of the pentagon, and then somehow set it off, that would be an amazing feat indeed. Yet, it would be a truly terrible one.

Is it though? A feat is a deed that’s difficult to achieve, but I don’t think it is inherently passing a value judgement as well.

Why? Triumph has the connotation of being a notable victory, but nothing about the character of the winner or the consequences. If the Nazis had won the war, wouldn’t that aptly be described as an appalling triumph?

I agree. The definition is “an achievement that requires great courage, skill, or strength.” There’s nothing about it being necessarily good or positive. Granted, that is how it’s often used, but modifying it with the word “terrible” whether it meaning "bad’ or “inducing terror” doesn’t make it an oxymoron. It merely qualifies what type of feat it is. I don’t see any oxymoron here.

ETA: Well. hold on. Etymonline has this line in the entry for “feat”:

Sense of “exceptional or noble deed” arose c. 1400 from phrase feat of arms (French fait d’armes).

In that case, if the Shakespearean usage does intend the “noble deed” definition, then it may well be oxymoronic.