Definition of "stiffly"

'Twas Mr. Glennie who first moved to seek me; for when the second day came that I was not at school, he thought that I was ill, and went to my aunt's to ask how I did, as was his wont when any ailed. But Aunt Jane answered him stiffly that she could not say how I did.

1898, J. Meade Falkner, chapter 5, in Moonfleet, London, Toronto, Ont.: Jonathan Cape, published 1934

'Very well, Clara,' she said stiffly, 'but I shall also speak to your father.'

1956 , Johanna Spyri, Heidi, translation of original by Eileen Hall, page 86