Bairn has broad Scots recognition

It means child and is strongly associated with Scots and northern English speech.

Wean is especially associated with the west

It is common in west-central Scotland, including Glasgow, but not universal.

Wee yin is descriptive and flexible

It literally means little one and can refer to a child or the smaller of two people or things.

Tone can be affectionate

All three may sound warm in family speech, but adult-directed use can feel patronizing.

Related dictionary entries

Common questions

Are bairn and wean exactly the same?

They often share the meaning child, but their regional distribution and tone differ.

Can wee yin refer to an adult?

Yes, when identifying the smaller or younger person, often playfully.

Which word should a visitor use?

Follow local usage rather than forcing a regional term.

Sources and further reading