http://dictionary.oed.com/cgi/entry/50096762?...good-bye1. As an exclamation: A form of address at parting; farewell.
Also in to bid, say good bye (to).1573-80 [see 2]. 1588 SHAKES. L.L.L. III. i. 151, I thanke your worship, God be wy you. 1591 {emem} 1 Hen. VI, III. ii. 73 God b'uy my Lord. 1600 HEYWOOD 2 Edw. IV, Wks. (1874) I. 141 Gallants, God buoye all. 1602 SHAKES. Ham. II. ii. 575, I so,
God buy' ye [1604 Qo. 2
God buy to you].
1607 MIDDLETON & DEKKER Roaring Girl Djb, Farewell.
God b'y you Mistresse Gallipot. a1652 BROME City Wit I. ii. Wks.
1873 I. 289 Heartily Godbuy, good Mr. Crasy. a1659 CLEVELAND Lond. Lady 54 But mum for that, his strength will scarce supply His Back to the Balcona, so God b' wy. [1668 PEPYS Diary 6 Aug., To Mr. Wren, to bid him ‘God be with you!’]
1694 Acc. Sev. Late Voy. II. 152 He flings up his tail..and so bids us good-b'wy.
1707 E. WARD Hud. Rediv. II. II. 6 So to a Feast should I invite ye You'd stuff your Guts, and cry,
Good bwi't'ye. 1719 D'URFEY Pills III. 135 Good B' w' 'y! with all my Heart.
1811 W. R. SPENCER Poems 141 When How-d'y-do has failed to move, Good-bye reveals the passion! 1818 BYRON Juan I. ccxxi, And so your humble servant, and good-b'ye! 1860 TYNDALL Glac. I. xviii. 122 We then bade Ulrich good-bye, and went forward. 1874 F. C. BURNAND My time x. 87 Then he said good-bye to me..and so left me.
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goodbye also: good-bye --- der Abschied
goodbye also: good-bye --- das Adieu
goodbye also: good-bye --- das Lebewohl
to say good bye --- sich verabschieden
to say good-bye to so./sth. --- sich von jmdm./etw. verabschieden
to say good bye --- auf Wiedersehen sagen
to throw a good-bye party --- seinen Ausstand feiern
goodbye also: good-bye --- ade
Goodbye also: Good-bye! --- Adieu!
goodbye also: good-bye --- tschüss
goodbye also: good-bye --- auf Wiedersehen
goodbye also: good-bye --- lebe wohl [form.]
Good bye! --- Auf Wiedersehen!
Good bye! --- Leb wohl! You can say good-bye to that. --- Das kannst du dir in den Wind schreiben.