imponderable

comparative more imponderable · superlative most imponderable

1. Not ponderable; without sensible or appreciable weight; incapable of being weighed.
2. Difficult or impossible to comprehend or evaluate.

plural imponderables

1. natural sciencesA substance or body, which is not ponderable, i.e., which not does not having a detectable amount of matter or measurable mass. An imponderable substance or body; specifically, in the plural, a name formerly applied to heat, light, electricity, and magnetism.
2. An imponderable question.
3. A factor that cannot be anticipated.

   One key imponderable is the attitude of the companies that will no longer have a role in the business. It is worth noting here that several have already thrown the towel in or been gently pushed out, such as Stagecoach and National Express.

   2024 July 10, Christian Wolmar, “The future of the rail franchises is certainly uncertain”, in RAIL, number 1013, page 50