"Illness" is a vague term for someone being sick of anything. "Sickenss" is also vague and simply describes someone condition. Some may consider this to have a stronger meaning than illness. "Disease" describes medical conditions that have been well documented and are very specific. This is why nearly all diseases have given names.

"Sickness" is when you have a cold or fever. Ex: "I have a sickness" or "I am sick" "Disease" is a less common of a term and usually means when someone is drastically sick. Ex. "I have a disease." Also, I disease is a sickness. And in this sense, is as common as "Sickness'' Ex. "The flu is a disease." "That is a disease." "Illness" is a less common term and is like ''Disease." Ex: "I have an illness." You may also say, "I am ill." and this is usually used with as sickness that is more life threatening.

Like Ty said, "Sickness" and "illness" are vague terms. They describe the state of feeling or being sick. A disease is actually the condition you have that makes you feel sick. Disease is the cause, sickness is the effect. Note: you can have sickness without disease: For example, a "hangover" is the sickness that often comes the morning after heavy alcohol consumption. It would never be called a disease. You could also have a disease without sickness. Some people are carriers of a virus or bacteria that never gives them any symptoms or bad effects but they can still pass it on to others, who will become sick.

disease is the alternation of the health of a living being. Disease is defined by a cause, the symptoms, clinical and paraclinic signs, the evolution, the prognosis and treatment.sickness include nausea, vomiting other common signs and a general feeling of discomfort and not feeling well. Illness is a state of poor health :)

disease is the alternation of the health of a living being. Disease is defined by a cause, the symptoms, clinical and paraclinic signs, the evolution, the prognosis and treatment.sickness include nausea, vomiting other common signs and a general feeling of discomfort and not feeling well. Illness is a state of poor health :)