Valediction, n.
Etymology: [L., valedicere, valedictum, to say farewell; vale farewell (imperative of valere to be strong or well) + dicere to say. See Valiant, Diction.]
A farewell; a bidding farewell. Donne.
Shades of meaning
Fernald has no entry of its own for valediction; he lists it under farewell.
Where he writes about it:
Valediction is a learned word never in popular use. — from farewell
Antonyms
none given