All 3 Uses

resignation
in
Harry Potter (#2) and the Chamber of Secrets
(Edited)

"Yes," said Harry heavily, resigned to explaining the complicated rules of Quidditch.
p. 106.9

resigned = as though having accepted something unpleasant as unavoidable
Mr. Lucius Malfoy, a governor of Hogwarts School of Witchcraft and Wizardry, where the enchanted car crashed earlier this year, called today for Mr. Weasley's resignation.
p. 222.1 *

resignation = quitting from his position at work
Ron sighed as though resigned to the worst, "I'm ready. Let's go."
p. 272.4 *

resigned = having accepted something undesired as unavoidable

Definitions:

(1) (resignation as in: submitted her resignation)
to quit -- especially a job or position; or a document expressing such an act
(2) (resignation as in: accepted it with resignation)
acceptance of something undesired as unavoidable or the lesser of evils
(3) (meaning too rare to warrant focus)
To resign can also more specifically mean to surrender or give up as in "I was clearly going to lose the chess game, so I resigned;" or "She resigned all pretense."