valediction

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++val·e·dic·tion /ˌvæləˈdɪkʃən/ noun [countable, uncountable] formal  GOODBYEthe act of saying goodbye, especially in a formal speech 〔尤指正式讲话中的〕告别，告别致辞 → farewell

Examples from the Corpus

valediction• It sounded more like a courtesy than a threat, a valediction.• Yet there was not even a hint of valediction in last week's speech on Capitol Hill.• Agassi's victory speech had more than a touch of valediction.

val·e·dic·tion nounChineseSyllable  

Corpus in of act the a formal goodbye, especially saying

valediction
val‧e‧dic‧tion /ˌvæləˈdɪkʃən, ˌvælɪˈdɪkʃən/ noun [uncountable and countable] formal
the act of saying goodbye, especially in a formal speech ⇨ farewell

val·edic·tionBrE /ˌvælɪˈdɪkʃn/ 🔊NAmE /ˌvælɪˈdɪkʃn/ 🔊 noun [countable, uncountable] (formal) the act of saying goodbye, especially in a formal speech （尤指正式演讲中的）告别，告别辞