Of, or pertaining to, spectres; ghostly.
Of, or pertaining to, spectra; classified according to frequency or wavelength (of light etc)
Existing or operating without involvement by the body; solely mental or intellectual; “ungrounded”, “heady”.
Not united in a regimented structure; lacking structure and order.
Not expressed or exhibited in material or concrete form; wholly abstract.
Not incorporated into a coherent system; conceptually disconnected.
Incorporeal; not possessed of a body.