Definition of "thoughtfully"

I opened my eyes, and the first thing they fell on was the venerable countenance of our old friend Billali, who was seated by the side of the improvised bed upon which I was sleeping, and thoughtfully stroking his long beard.

1886 October – 1887 January, H[enry] Rider Haggard, She: A History of Adventure, London: Longmans, Green, and Co., published 1887

'That button, it suggests possibilities,' said Poirot thoughtfully.

1934, Agatha Christie, chapter 4, in Murder on the Orient Express, London: HarperCollins, published 2017, page 105