imponderable

(im-pon‘dér-a-bl), a. and. [= F. impondérable = Sp. imponderable = Pg. imp on der avel = It. imp on der a bile; as in-3 + ponderable.] I, a. Not ponderable; not capable of being weighed; without gravity. No one wave of this imponderable medium [ether] can give the requisite motion to this atom of ponderable matter. H. Spencer, Prin. of Biol., § 13. Spirit, which floods all substances with its life, is the solvent force quickening the imponderable e ences. Alcott, Table-Talk, p. 129. II. 2. In physics, a thing which has no weight: a term formerly applied to heat, light, electricity, and magnetism, on the supposition that they were material substances, and still used of the hypothetical universal medium, ether.