A. A. Milne, Winnie-the-Pooh (1926):
Winnie-the-Pooh.
When I first heard his name, I said, just as you are going to say, ‘But I thought he was a boy?’
‘So did I,’ said Christopher Robin.
‘Then you can’t call him Winnie?’
‘I don’t.’
‘But you said—’
‘He’s Winnie-ther-Pooh. Don’t you know what “ther” means?’
‘Ah, yes, now I do,’ I said quickly; and I hope you do too, because it is all the explanation you are going to get.