commencement
noun uk/kəˈmens.mənt/ us/kəˈmens.mənt/
[ C or U ] formal开始；开端
the beginning of something
Would passengers please turn off their mobile phones before the commencement of the flight. 请乘客们在飞机起飞前关闭手机。
[ C ] US学位授予典礼;毕业典礼
a ceremony at which students formally receive their degrees