lullaby
noun
[ ˈlʌləbʌɪ ]
• a quiet, gentle song sung to send a child to sleep.
lullaby
verb
• sing to (someone) to get them to go to sleep.
• "she lullabied us, she fed us"
Origin:
mid 16th century: from lull + bye-bye, a sound used as a refrain in lullabies; compare with bye-byes.