ponderous (adj.)

c. 1400, "thick;" early 15c., "heavy, weighty, clumsy by reason of weight," from Latin ponderosus "of great weight; full of meaning," from pondus (genitive ponderis) "weight," from stem of pendere "to hang, cause to hang; weigh" (from PIE root *(s)pen- "to draw, stretch, spin"). From late 15c. as "important." Meaning "tedious" is first recorded 1704. Related: Ponderously; ponderousness; ponderosity (1580s in the figurative sense).