Let's assume two people A and B are in an argument, when A accuses B of some wrongdoing, which B denies. A while after, B, for the sake of pretending to have a moral high ground (for thinking of ending the argument), agrees to the wrongdoing, just for the sake of it, while making it clear in their tone (which has an inflection similar to that of sarcasm), that A is in fact wrong. Is there an another word for such admittance or such a behavior?
If you say so
a weak or indifferent agreement. If one has an opposing opinion as you, but they’re tired of arguing or raising points, the person can result to saying ‘if you say so’ sarcastically which serves as a weak agreement to stop the ongoing argument. (source)
used to convey lack of agreement together with a refusal to enter into or continue an argument.
whatever adverb (DISRESPECT) informal
something that is said to show that you do not respect or care about what someone is saying, especially someone who is asking you to agree with them or agree to do something
Whatever you say.
Tom Dalzell, Flappers 2 Rappers: American Youth Slang (1996) lists whatever under the category "Exclamations" in the chapter on "The 1970s and 1980s":
Whatever. While I may not agree with what you just said, I do not choose to waste my time arguing with you about it just now.
Agree to disagree
to agree not to argue anymore about a difference of opinion. He likes golf and his wife likes tennis, so when it comes to sports, they have agreed to disagree. (M-W)
B says, "Let's agree to disagree." B has not admitted to any wrongdoing, and cuts off debate.
We might call that sardonic or passive-aggressive.
A more formal term that doesn’t connote sarcasm would be acquieescence, which Merriam-Webster defines as:
passive acceptance or submission
We could also say that he accedes or is resigned. Again, neither of those connotes sarcastic agreement.
Not an exact match, but this often takes the form of a fauxpology or non-apology.
The classic example is
I'm sorry you feel that way.
Which sounds like a sincere apology but on closer examination turns out to be implying that the other person's feelings are unreasonable.
used when you do not believe what someone has said:
"I always miss you when I go away ." "Yeah, right!"
Depending on the tone and rhythm used by person A, it could actually mean anything between 100% agreement and 100% disagreement. Without any other indication, it should probably be understood as being sarcastic.
Here's a related joke.
My first thought was "paying lip service" or "to pay lip service"
pay lip service to something
to say that you agree with something but do nothing to support it: She claims to be in favour of training, but so far she's only paid lip service to the idea.
Another option is capitulate.
1 a: to surrender often after negotiation of terms
The enemy was forced to capitulate unconditionally.
b: to cease resisting : ACQUIESCE
The company capitulated to the labor union to avoid a strike.
2 archaic : PARLEY, NEGOTIATE
To capitulate is basically to fold* your argument in general, but not necessarily sarcastically. It can definitely be done in a manner derogatory to the other person or people in the conversation, but that's not inherent to capitulating. As the definition says, it's more to admit defeat than to be snarky, so it may not be the best option. However, you can be disrespectful when you are saying you are capitulating.
"I always have to capitulate to your narcissism, you SOB."
* Fold definition (also another option):
6a: to concede defeat by withdrawing (one's cards) from play (as in poker)
b: to bring to an end
You can also say "I fold, I give up", or something similar, to show your displeasure with their form of arguments.
no contest, or nolo contendere
is used when a defendant agrees to pay the fine or other penalty for some crime, just to get it over with, without actually admitting guilt.
Sometimes a person uses the phrase sarcastically outside the courtroom -- that person at the same time (a) agrees to do the thing the other person wants, but (b) without admitting that other person is right, and simultaneously (c) sarcastically implying that other person is making too big of deal (practically a criminal offense) out of something not that important.