pensive
PEN-sivadjMeaning quietly and deeply thoughtful, often a little sad
Memory hook PEN-SIVE: chewing the PEN, lost in thought. Lila sits by the rainy window chewing on her pen, thinking about the friend who moved away; she is quiet and pensive.
On the last day of camp, the pensive campers watched the lake in silence.
In context Usually chatty at dinner, Grandpa was pensive that night, gazing out the window and answering every question with a faraway smile.
Similar thoughtful, reflective, wistful, meditative
Opposite carefree, lighthearted, thoughtless
From French pensif, from penser (to think), from Latin pensare (to weigh, to ponder).