If I use principal when I mean principle, is that a spelling error or grammatical error?
It seems a spelling error to me but a friend argues that it is a grammatical error because I used the wrong word.
If I use principal when I mean principle, is that a spelling error or grammatical error?
It seems a spelling error to me but a friend argues that it is a grammatical error because I used the wrong word.
It's neither of them really. It's a lexical error, meaning an error in choice of words. Grammatical errors are really just violations of the patterns of our language. Spelling errors are unintentional, so if you are really convinced you're using the right word, it doesn't count (thus they can be hard to differentiate from lexical errors in finished works, but that's what proofreaders and editors are for.)
It's a spelling error. As you said, you meant "principle". You just spelled it "principal". If you'd spelled it "principel", there wouldn't be any question about the type of error. The fact that your misspelling happens to be another word doesn't change the nature of the error.
Consider these two examples:
"I like the read convertible." - Did I misspell "red" or did I choose the verb "read" or its adjectival form? Most people would say that I misspelled "red". Why? 1) Very few people would think the verb "read" makes sense in this sentence, so they wouldn't expect me to mistakenly choose it. 2) No one expects me to confuse "red" and "read".
"I have to catch the buss at 10 o'clock". Did I misspell "bus" or did I choose the word "buss" (n. kiss https://www.dictionary.com/browse/buss). Again, most people would say that I misspelled "bus". Why? 1) Except in a very specific context, using "buss" wouldn't make sense, so I wouldn't be expected to choose it. 2) No one expects me to confuse "bus" and "buss".
Is "principal/principle" different than "red/read" and "bus/buss" in a way that would change the type of the error? I don't think so. Errors with "principal/principle" are obviously much more frequent than the others, but the frequency of an error doesn't change its type. Some people don't realize that "principal/principle" are two different words. While this would rarely be the case for "red/read", it would usually be the case for "bus/buss" and as noted above, this is a spelling error. People often have trouble remembering which is which even after the difference is pointed out. While this is true, the point of confusion is that people can't remember whether "a fundamental law or truth" is spelled "principle" or "principal" and whether "first or highest in rank" is spelled "principle" or "principal", i.e. a spelling issue.
Definitions adapted from https://www.dictionary.com/browse/principle and https://www.dictionary.com/browse/principal.
Spelling error; both are different words
Principle is a noun; principal is an adj., except in cases like School Principal.