Lull
Middle English: imitative of sounds used to quieten a child; compare with Latin lallare ‘sing to sleep’, Swedish lulla ‘hum a lullaby’, and Dutch lullen ‘talk nonsense’. The noun (first recorded in the sense ‘soothing drink’) dates from the mid 17th century.
wiktionary
From Middle English lullen, lollen. Originally, perhaps expressive in origin from la-la-la or lu-lu-lu sounds made in calming a child.
Cognate with Scots lul, lule, loll(“to lull, put to sleep, howl, caterwaul”), Dutch lollen(“to sing badly, caterwaul”), Dutch lullen(“to chatter, prate, cheat, deceive”), Low German lullen(“to lull”), German lullen(“to lull”), Danish lulle(“to lull, sing to sleep”), Swedish lulla(“to lull”), Icelandic lulla(“to lull”).
etymonline
lull (v.)
early 14c., lullen "to calm or hush to sleep," probably imitative of lu-lu sound used to lull a child to sleep (compare Swedish lulla "to hum a lullaby," German lullen "to rock," Sanskrit lolati "moves to and fro," Middle Dutch lollen "to mutter"). Figurative use from 1570s; specifically "to quiet (suspicion) so as to delude into a sense of security" is from c. 1600. Related: Lulled; lulling.
lull (n.)
1650s as the name of a soothing drink, from lull (v.). Meaning "temporary period of quiet or rest amid turmoil or activity" is from 1815.
