IMPONDERABLE

a. n.

2 definitions — Webster’s Dictionary (1828)


1.
a.

Not ponderable; without sensible or appreciable weight; incapable of being weighed.

2.
n.

An imponderable substance or body; specifically, in the plural, a name formely applied to heat, light, electricity, and magnetism, regarded as subtile flyids destitute of weight but in modern science little used.