Ponderous is ultimately from the Latin word for "weight," namely, "pondus" (which also gave us "ponder" and "preponderance" and is related to "pound").

Where did the word pondering come from?

It comes from ponderare, which literally meant to weigh, and pondus, which means weight. People sometimes use the word ironically, for example, when someone asks you to do something you really don't want to do. You may tap your chin for a second and say, "Let me ponder that." Pause.

Does ponderous mean heavy?

of great weight; heavy; massive. awkward or unwieldy: He carried a ponderous burden on his back.