pensive (adj.)

late 14c., pensif, "sad, sorrowful, melancholy;" also "engaged in serious thought, meditative, contemplative;" from Old French pensif "thoughtful, distracted, musing" (11c.), from penser "to think," from Latin pensare "weigh, consider," frequentative of pendere "to hang, cause to hang; weigh; pay" (from PIE root *(s)pen- "to draw, stretch, spin"). Meaning "expressing thoughtfulness with sadness" is from 1540s. Related: Pensively; pensiveness.