Interested in Language
"You must turn in your homework UNTIL next Sunday."
"You must.................................BY next Sunday."
Do these two sentences mean exactly the same as one another?
Tbe problem is that even the most logical of us often refer to the next Sunday coming as something other than "next Sunday", and when we do say "next Sunday" we often do not mean the Sunday in future closest to now.
And it gets worse. Today is Friday 14th (for me). "Next Sunday" could easily be Sunday 23rd; even if on Monday 10th, "next Sunday" might have been Sunday 16th. So, "next Sunday" can change date even if there is no intervening Sunday.
Usages are local and dependent on context. "I can't make it this weekend. Let's make it next Sunday" - obviously "next Sunday" here is the one after next. Even spouses fight over this if their preferred usage is different.
PS: "Sunday next week" is also not good unless you know which day the hearer's week begins. Ours (Australia) begins on a Sunday, so "Sunday next week" is strictly Sun 16th.
For clarity, whether in class, at work or simply making plans with your friends, give the date! Unless it's tomorrow or the day after tomorrow (in which case you can use those terms), it's much easier to say "See you on the 18th". It doesn't matter what day of the week it is - if everyone knows the date, there can be no confusion.
I'm not saying that native speakers actually do this, of course. That would suggest we practise what we preach!
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.