1. Etymology and entomology
I like this one. It's funny.
2. Ignorance, stupidity and apathy
Q. What's the difference between ignorance and apathy?
A. The sadist says 'no'. No, wait, wrong joke. I don't know and I don't care.
3. Apathy, anthology, anthropology, archaeology, Indiana Jones, and paleontology
You'd think this would be easy. Even if you ignore the first two.
4. WWW and HTTP and HTML, and 'web', 'teh infobahn thingy' and 'the internet'
Yeah, ok, not disjoint, but still distinct. Though while we're on the subject, why do some websites still require you to prefix, or not prefix foo.com with www? If the place is too small or too large for 'www.foo.com' to refer to a single computer, is it that useful?
5. Ie and eg
I don't want to get into just spelling mistakes, though I used to be baffled by this one. You don't need to know the latin to remember what a two letter word means. Is it because they're short? No-one I've let live has ever written 'me' or 'aa' when they mean 'ie'.
But in fact, people confuse even the long hand versions. Often the best way to convey a definition *is* with an example, and if you just want to check someone can use the word it's great, but you need to be aware that it's not quite a definition because you're relying on the listener to fill in the blanks. I remember at school I was generally last when asked to define a word, because I kept trying to define them, rather than yelling "It's like when someone says 'foo'".
6. Maths and arithmetic.
7. =, ==, =~, eq, ~, ≡, ≈
I need to write a test "what sort of comparator are you." Though it's worth noticing that sometimes these *are* the same, at which point you get some fun maths.
. 99 to 1 and one in ninety-nine.
9. Atheist, agnostic, skeptic, luddite and heathen
I once had someone quite seriously correct me by saying atheists don't believe in souls or an afterlife. Now, fair enough, all the atheists *I* know are athiests because they're skeptics and as yet unconvinced by the evidence for God, but there's plenty of people who don't believe in a god for whatever reason, but do believe in things *I* would think are supernatural and/or stupid.
This one hadn't occurred to me until I saw the disclaimers on some skeptic websites, but they felt it necessary to say that skeptic didn't mean 'reject everything new' but 'hold in abeyance anything without supporting evidence'.
Atheist and agnostic is a tricky one, because it depends on your definitions, especially once you get into 'strong' and 'weak'. The one thing everyone but me seems to agree on is that these terms are well defined, but not *how* they're defined[1].
10. Nine and ten.
[1] NB: There's a lot to be said for using the original meaning, the logical entomologic[2] meaning, or the commonest meaning, but when you can't just look the answer up in a dictionary it can be helpful to qualify your speech. Though I suppose that means I can't use 'literal' now because no-one knows what it means.
[2] Deliberate joke.