ruminate about (something)
To give great consideration to something; to ponder on or think about something very deeply. We sat ruminating about various ways to improve our business model when Janet suddenly came up with a brilliant idea. Well, your review has certainly given me plenty to ruminate about.
ruminate about something
and ruminate on somethingto ponder and think about something. (Alludes to a cow, relaxing and chewing its cud, as if it is thinking.) He sat, ruminating about the events of the day, humming and eating peanuts. Let me ruminate on this a little bit.