1 [uncountable and countable]BE when you officially announce that you have decided to leave your job or an organization, or a written statement that says you will be leaving [↪ notice]:
hand in/tender your resignation (=officially say that you want to resign)
2 [uncountable] when someone calmly accepts a situation that cannot be changed, even though it is bad :
She gave a sigh of resignation.
She gave a sigh of resignation.