1. reflect deeply on a subject

I mulled over the events of the afternoon; philosophers have speculated on the question of God for thousands of years; The scientist must stop to observe and start to excogitate

2. heat with sugar and spices to make a hot drink

mulled cider

Thanks to "Artha - The Open Thesaurus" I have a choice: Mull as meaning #1; or Mull as meaning #2.