Adieu (2,4)
'adieu' is the definition.
(synonyms)
This is all the clue.
(Other definitions for so long that I've seen before include "Informal goodbye; see you" , "Bye for now!" , "Ta-Ta!" , "Goodbye (colloq.)" , "Cheerio, bye-bye" .)
'adieu' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for goodbye that I've seen before include "Cheers" , "Farewell remark" , "parting" , "Cheerio" , "Adieu" .)