Source : Webster's Revised Unabridged Dictionary (1913)

Unwellness \Un*well"ness\, n.
   Quality or state of being unwell.

Source : WordNet®

unwellness
     n : impairment of normal physiological function affecting part
         or all of an organism [syn: {illness}, {malady}, {sickness}]
         [ant: {health}, {health}]