Ruminate (verb)

1. To think deeply about something; to ponder.
2. To chew the cud, as a ruminant animal does.

Origin:

From the latin word ruminare, which means "to chew the cud".

Examples:

1. He spent hours ruminating on the problem, trying to find a solution.
2. She ruminated over her mistakes and tried to learn from them.
3. The cow was ruminating in the field.
4. He was ruminating on the events of the day.
5. She had to ruminate on the decision before making up her mind.