I read a comment in a post (meaning of the phrase "some kind of X") just now and learned an expression "I neither know nor care".
I would like to know whether the expression formal or informal.
I searched the expression on cambridge (https://dictionary.cambridge.org/spellcheck/english-chinese-simplified/?q=I+neither+know+nor+care) and oxford (https://www.oxfordlearnersdictionaries.com/spellcheck/english/?q=I+neither+know+nor+care), none of them has this item.
I am aware that not being included in cambridge does imply necessarily informal, though I don't know somewhere else I can check this.
Is there an easy way to check if an expression formal or informal?
If formal/informal sounds like a matter of opinion, I would prefer the expression in a textbook as formal.
Best Answer
Whether an expression is formal or informal can be very much a matter of opinion, and the classification can change over time, usually in the direction of the informal becoming formal.
"I neither know nor care" is quite grammatical. It is not slang. It is certainly dismissive, and so would not be polite in all circumstances. But it is capable of bearing a serious meaning.
Hansard Online shows that the expression "neither know nor care" has been spoken in the UK Parliament three times since February 2015. Being spoken in formal proceedings by a legislator is obviously not an infallible test of the formality of an expression, but it is suggestive that this expression is not particularly informal.
As the above might indicate it is not necessarily easy to check if an expression is in formal use. Sometimes it is obvious, but there will be cases that are debatable. My opinion, for what it is worth, is that this expression would be accepted as formal usage.