la-la Look up la-la at Dictionary.com
syllables used to make nonsense refrains in songs; compare Old English la, a common exclamation; but la-la is imitative of babbling speech in many languages: Greek lalage "babble, prattle," Sanskrit lalalla as an imitation of stammering, Latin lallare "to sing to sleep, lull," German lallen "to stammer," Lithuanian laluoti "to stammer."