Quick, what’s wrong with this sentence:
I saw three octopuses yesterday.
If you said ZOMG THE LETTERS ARE ALL SLANTY then you, sir/madam, are correct. Your prize is a deep but ephemeral satisfaction.
However, if you said that “octopuses” should be “octopi,” you would be oh my goodness so very wrong.
I always thought it was “octopi” too. Turns out, the word “octopus” has no fewer than three different plurals, which I list here (no joke) in order of descending correctness:
octopuses – the most obvious plural, and the one you should actually use.
octopodes – the “proper” plural, or at least it used to be. Generally considered pedantic.
octopi – some overzealous grammar nazi came up with this rule by guessing that “octopus” was Latin and took the same form as other Latin plurals (ex. “locus” -> “loci”). Somebody was wrong. Enough people now mistakenly use “octopi” that it’s actually in the dictionary, but it’s not preferred usage.
Can I first say how utterly insane it is that English has a word with three different plurals, all of which are in the dictionary, but which have a hierarchy of correctness? Or that, if there existed somebody else in the universe crazier than I am, he could probably debate the order I’ve chosen? Yeah. English. Seriously.
Beyond that, think about it: there’s a whole class of language rules where people go around “correcting” perfectly good English into bad English. “Octopuses” -> “octopi” is only one example. You’ve also got:
People who never end a sentence with a preposition, apparently because they are fans of 18th-century bishop Robert Lowth.
People who never split infinitives, apparently because they hate Star Trek. (To boldly go…)
People who say “She gave it to Bob and I” instead of “She gave it to Bob and me,” because the latter sounds less proper (even to me) for reasons I don’t fully understand.
And because English is batshit crazy, we actually have a word for this kind of incorrect correction: “mumpsimus.” Dictionary.com defines it as:
adherence to or persistence in an erroneous use of language, memorization, practice, belief, etc., out of habit or obstinacy
(The plural is “mumpsimuses,” smartass.)
Ha! Crazy, right? Man, next thing you know, we’ll have a word for people like me, who straighten out the people who make incorrect corrections. Ha ha!
Wait, this is English. Of course there’s a word for that. “Sumpsimus.” No, I’m not making it up.
Oh, English, you magnificent bastard. I can’t stay mad at you.