Incapable of being perceived by the senses; incorporeal.
Anything intangible
Incorporeal property that is saleable though not material, such as bank deposits, stocks, bonds, and promissory notes
Being, or having the salient properties of, a monotone function.
Having a single unvaried pitch.
To speak in a monotone.
A piece of writing in one strain throughout.
A single unvaried tone of speech or a sound.