… But you’re not allowed to say “literally.” That’s too easy.
What word can you think of that people sometimes use despite not knowing what it actually means? I’ll start:
Bemused. Often used (including on this board) to mean “mildly amused” or “Caused to be amused.” It actually means to not understand something; the usual synonym given is “bewildered.” It can also mean to be preoccupied so as not to notice something.
Inconceivable.
Enormity: many people assume it just means really big or extensive. The original definition is outrageous, heinous or atrocious. Dictionary.com lists the “big” definition as well, so I guess the meaning is shifting.
Nonplussed. It does mean confused, or at a loss, but people often think it means indifferent towards. (Maybe confusing it with nonchalant?)
Barter. So many people use it when they mean ‘haggle’ or ‘bargain’.
I’ve also seen ‘weary’ (tired) for ‘wary’ (suspicious).
Quantum. It’s not a huge difference, it’s the smallest measurable difference.
Decimate.
Momentarily.
I teach freshman comp, so I have a lot of these. Two that are approaching pet peeve status:
Droll. A remarkable number of my students, including many of the better ones, seem to think it means “dull.”
Humored. Lots of freshmen try to use it as a synonym for “amused.”
Penultimate.
Inflammable.
Niggardly. It means “miserly,” but I would not use it.
Don’t let the morons win. I’d use it, and laugh in the face of anyone who was offended by it through ignorance.
“Prevaricate” is a good one. It often seems to be used to mean something like “hesitate” or “procrastinate”.
Also I increasingly see “erstwhile” used as if it meant “dignified” or “upstanding”.
What about those who over-hear you, and go away thinking you are ‘that kind of person’?
I know: More fool them. But can you blame them for not being as wise as you for knowing what the word ‘Niggardly’ really means? I never knew it meant anything other than “Like a nigger” (until now)
As far as I know it means last but one. What do people often mistake it to mean?
If they’re the kind of person who forms that sort of opinion based on one word which they don’t understand, I don’t think they’re the sort of person whose views bother me!
I don’t think it has ever meant that, though most people think it does. Just say “Scrooge was really niggardly” and see what type of comments you get. It is definitely a negative word, and it sounds racist, even if it isn’t
While I agree that the scientific definition is smallest difference, it also means a huge difference, a step in magnitude.
Until I read about that senator or whoever it was that got in trouble for using it, it had never even occured to me that it might sound racist. It’s just people looking for offence where there is none to be taken.
I always associated it with “niggling”, and I see the two words are related.
Should I avoid the word “niggle” as well? 
Apologist.
‘a person who defends, in speech or writing, a faith, doctrine, idea, or action’
is not a derogatory term.
Disinterested.
It does not mean not interested in. Though rather like decimated, which got used (rather pointedly) correctly on Doctor Who of all places, I expect so many people use it to mean the wrong thing then it’s too late to save.
disinterested:
While it can mean a lack of interest (as in uninterested), many of the times the speaker means to convey “unbiased” (a second definition), the listener interprets it as “uninterested”.
ETA: Wicked simulpost!
Awhile ago, I googled “niggardly.” Among the first 50 hits, 49 of them were about the controversy over how “niggardly” is used. One of them used the word in a car review, and explained parenthetically the word’s etymology. Unless I’m willing to do what the car review did–step back and take the time to explain the word’s origin–I don’t think “niggardly” will ever be an effective tool of communication for me. Same goes for nearly everyone, IMO.
BUt to the thread:
-Enervate means to sap of energy, not to energize.
-Livid means pale, not full of color.
Daniel