mull over
     v : 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" [syn: {chew
         over}, {think over}, {meditate}, {ponder}, {excogitate},
         {contemplate}, {muse}, {reflect}, {mull}, {ruminate}, {speculate}]
Source: WordNet® 2.0