Translation:The button is big, but not round.
Do you mean this sort of thing?
"You haven't given me the money yet." "Doch, I gave it to you yesterday."
This kind of "doch" isn't really identical with the one that means "but" (historically, it likely is; but in actual usage, it feels like a word of its own to me). It's a "yes" that puts a negation right:
"You didn't do what I said." "Yes, I did." "Didn't you go there yesterday already?" "Yes, but I liked it so much I went again." "I wasn't there." "Yes, you were."
"Do you think they have a room for us? The hotel must be fully booked this time of year." "Yes, I'm sure they'll have a room left." (Here, it's not a straight negation the "doch" puts right, but it's more like making a point against a doubt.)
(Bonus note: for "Yes [, I did / it was, etc], but [still]..." you can also use "Schon, aber..." - or even both: "Wasn't this nice?" "Doch, schon. But I still say we shouldn't have spent all that money.")
I understood it in this way: if something is going not naturally, if it surprise you, then you use "doch". For example: "Er hat Hunger, doch er isst nicht". If it doesn't surprise you, if all is going naturally, you use "aber"". . Another way: if you can say "but it's yet still...", you use "doch".
I disagree... "Yet" is used when the previous clause would imply that something was supposed to happen, like "I asked five times for the money, yet he still hasn't paid me back." In this instance, you can't use "yet" because the fact that the button is big doesn't imply that it should also be round.
You’d use sondern when you’re saying that the subject is one thing -instead- of something else. Das Wetter heute ist nicht warm, sondern kalt, for instance. It can’t be both warm and cold; it has to be one or the other. Or Er ist kein Arzt, sondern Mechaniker.
Whereas with the button in the sentence here, it can be large and round, or large and not round, or not large and not round. Its size and its shape are not mutually exclusive. I might say that if I needed to find a button for my coat that is large and round. My friend looks in the button jar and says, “Here’s a button that might work. It’s large, but not round.” Der Knopf ist groß, aber nicht rund.
There are three reasons: First, there’s no second clause at all— aber nicht rund has no verb, so it’s a phrase and not a clause. Second, even if there -were- a verb, making the second half of the sentence a clause, it wouldn’t be a subordinate clause. Aber is a coordinate conjunction like und. Third, if it were a subordinate clause, then the verb would move to the end of the clause, and not the word nicht.
That’s because the last letter in groß is
not a capital B, and a capital B cannot be used as a substitute for it. It’s the character for a double S after long vowels. The German name for ß is ess-tsett, or scharfes s.
You get one of those letters on a phone or iPad by a long touch on the regular s, which brings up the various alternative characters. Select the ß.
On a desktop PC, you can either just click the ß provided on the screen for us, or use Alt+0252.