but then

1 —used to introduce a statement that adds another and different thought to a preceding statement I'm surprised to hear that Tom has left the army. But then I suppose he never was the type to obey orders. ; sometimes used to introduce an explanation for something His cakes are amazing—but then he did study with some of the best pastry chefs in the world.

2 —used to introduce a statement that tells about something different or surprising that happened next The team won the first two games, but then failed to win any of the next five.