'lullaby' originates from Middle English, specifically the word 'lollai,' where 'loll' meant 'to lull' and 'by' was a common ending for songs.

'lollai' transformed into the modern English word 'lullaby' through gradual phonetic changes.

Initially, it meant 'a song to lull a child to sleep,' and this meaning has largely remained the same in modern usage.