good denyoudaoicibaDictYouDict[good den 词源字典]
salutation, Elizabethan corruption of good e'en, itself a contraction of good even "good evening," which is attested from c. 1500, first as gud devon, showing a tendency toward misdivision. See good (adj.) + even (n.).[good den etymology, good den origin, 英语词源]
good-byeyoudaoicibaDictYouDict
salutation in parting, also goodbye, good bye, good-by, 1590s, from godbwye (1570s), a contraction of God be with ye (late 14c.), influenced by good day, good evening, etc. As a noun from 1570s. Intermediate forms in 16c. include God be wy you, God b'uy, God buoye, God buy, etc.