Illth, coined by John Ruskin in the 1860s, is the reverse of wealth in the sense of ill being the opposite of well.[1][2]
In Ruskin's view:
Various other writers have used the term, and continue to do so. A notable example is George Bernard Shaw, who used illth as a subheading in an 1889 essay.[3]
In the context of modern economic theory and practice, the term has been central to the work of Herman Daly and his advocacy for a Steady-state economy.[4]