Illness (sometimes referred to as ill-health or ail) can be defined as a state of poor health. It's sometimes considered a synonym for disease. Others maintain that fine distinctions exist. Some have described illness as the subjective perception by a patient of an objectively defined disease. Introduction The mode of being healthy includes, as defined by the World Health Organization, " [...] a state of complete physical, mental and social well-being and not merely the absence of disease or ".… (More on Ailment)