Calmed or soothed someone into a peaceful or relaxed state, sometimes deceivingly into a false sense of security.
From Middle English 'lullen,' possibly from Old Norse 'lulla' (to sing), which is onomatopoetic, imitating the 'lul-lul' sounds used to soothe babies.
Lullaby and lull share the same ancient 'lul' sound—parents all over the world discovered that repeating low 'lul' sounds naturally calms babies, and languages preserved this in both the action (lull) and the song (lullaby)!
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