(a set of) formal acts, often fixed and traditional, performed on important social or religious occasions

a wedding/graduation ceremony 结婚／毕业典礼

very formal and polite behaviour

She arrived at the airport without the pomp and ceremony that usually accompanies important politicians. 她抵达了机场，没有通常与重要政界人士相伴的盛况和礼仪。

I handed her my letter of resignation without ceremony (= in an informal way). 我毫不客气地向她递交了辞职书。