im ‧ pon ‧ der ‧ a ‧ ble /ɪmˈpɒnd ə rəb ə l $ -ˈpɑːn-/ BrE AmE noun [countable usually plural] formal
something that cannot be exactly measured, judged, or calculated:
There are too many imponderables to make an accurate prediction.
—imponderable adjective :
an imponderable question