Difficult or impossible to comprehend or evaluate.
Not ponderable; without sensible or appreciable weight; incapable of being weighed.
An imponderable question.
A factor that cannot be anticipated.
An imponderable substance or body; specifically, in the plural, a name formerly applied to heat, light, electricity, and magnetism.
Incalculably, exceedingly, or immeasurably minute; vanishingly small.
Very small.
Of or pertaining to values that approach zero as a limit.
A non-zero quantity whose magnitude is smaller than any positive number (by definition it is not a real number).