In Scotland, and in much of the north of England too, a bairn is a child — a baby or a youngster. A mother might say the bairn is asleep. There it is warm, ordinary speech, not a joke and not old-fashioned; it is simply their everyday word, the way child or kid is for other people. Outside those places you mostly hear it in stories, songs, or when someone is putting on a Scottish voice. It is fond, not rude. Though actually it is a very old word, going back through Scots and older English to a Germanic root for a child. Scholars say it is a doublet of an old word barn that also meant child. That barn is not the farm building — the shed for hay is a different word that only sounds close.