(每日一词）valediction

Valediction  /ˌvæl.əˈdɪk.ʃən/ n. （尤指正式的）告别，告别词

meaning: the act of saying goodbye, especially formally, or a formal speech in which someone says goodbye 

1) 词根：vale-再见(value 价值) 

2) 词根：dict- 说话(dictionary 字典） 

3) 后缀：-ion 名词后缀