Lullaby
来自Big Physics
mid 16th century: from lull + bye-bye, a sound used as a refrain in lullabies; compare with bye-byes.
wiktionary
From Middle English lullen(“to lull”) + bye. First recorded circa 1560. Compare Old English bī, bī(“lullaby!”, interjection).
etymonline
lullaby (n.)
"soothing song sung to infants," 1580s, noun use of the words lulley by (1560s), from Middle English lollai or lullay, a common burden in nursery songs, from lullen (see lull (v.)). Second element perhaps from by in good-bye or simply a meaningless extension.
