Other forms: diseases
A disease is an illness with a known cause and a name. Heart disease, catch a disease, disease control.
It is the technical word: a disease has a definable cause and course, where illness is how it feels and sickness is the social role. Communicable diseases spread and non-communicable ones do not. Note diseased; and that the word is literally dis-ease, meaning the absence of ease — it meant discomfort long before it meant a named condition.
1noundiseaseAn illness with a known cause and a name.
“Washing your hands often helps to stop the disease from spreading.”
disease is an illness.
Old French desaise is des- plus aise, ease. Disease meant discomfort or trouble before it meant illness, and it displaced the Old English adl.
Old French
desaise
Anglo-Norman
desese
Middle English
disese
English, today
disease
From Middle English disese, from Anglo-Norman desese, from Old French desaise. From Middle English disese, from Anglo-Norman desese, from Old French desaise, from des- + aise. Displaced native Middle English adle (“disease”) (from Old English ādl (“disease, sickness”), see adle), Middle English cothe (“disease”) (from Old English coþu (“disease”), see coath). by surface analysis, dis- + ease.
Etymology from Wiktionary, CC BY-SA