Ponder
Definition 1 of 2
Pro Tip 1/3
Deep Reflection
Use 'ponder' when you need to express a deeper level of thought than just 'thinking'. He would often ponder the mysteries of the universe.
Pro Tip 2/3
Time-Intensive
'Ponder' implies you're spending a considerable amount of time on the thought process. She needed to ponder her choice of university thoroughly.
Pro Tip 3/3
Serious Matters
Commonly, 'ponder' is used for serious, often personal or philosophical topics. After the seminar, he stayed back to ponder over what he had learned.