Not static or stable.

Roget 320: light, subtile, airy; imponderous^†, imponderable; astatic^†, weightless, ethereal, sublimated; gossamery; suberose^†, suberous^†; uncompressed, volatile; buoyant, floating etc. v.; portable.    light as a feather, light as a thistle, light as air; lighter than air; rise like a balloon, float like a balloon ... meer laten zien