Pensive – Plunged in thought, thinking seriously about something.
The Pensieve bowl that Harry Potter used only worked if he plunged his face into the liquid to pull out thoughts.
Examples of pensive in a sentence
Pensive and troubled, she dressed for a difficult day.
He looked out for a long moment, pensive, before returning his attention to her.
To Dean, she seemed a tad pensive as she sat next to the window.